you're neutering the NC's damage all the more. So I can only do damage in the shortest band? And that's just on a cruiser. On a Grand Cruiser or Battleship, I'm doing nothing.
You'd be "doing nothing" with a single NC, which will hardly be the only weapon in your fleet.

D3+1 means 2, 3 or 4 points of damage on a hit; that means potentially taking down all the shields on any ship but a 6-spore hive ship, or taking down the shields of a grand cruiser on average, with one shot from a cruiser. How you are able to see that as "nothing" is beyond me, honestly.

It's just below the average of the current NC-rules, and once you take LO into account (which does squat for the current NC, BTW) the average actually gets higher in the closest range band.
Besides you seem to be missing that my take on the NC-rules is making it far more accurate; basically I'm illustrating the higher accuracy of shorter ranged shots by increasing the potential damage (just imagine the explosion being closer to the target vertically), not by decreasing potential scatter.

D6 potential damage works. You need to be really rolling good to do that 5 or 6 point damage. First you need to roll a hit, then you need to roll a 5 or 6. That combination is not easy to get.
It's not about the potential damage, it's about reliability. See the examples (there are two for a reason

) in my post above.

Next the BFI before the shot is just right.
After giving it a bit of thought I agree.
One does not decide to BFI when you know the shot will hit or not, especially from artillery type shots.
"Artillery"? In space? That's ... well, I never imagined NCs to work that way.

More like depth charges, just that they are not dropped but fired in a straight line, exploding after they've traveled a pre-set distance.
So a captain can see the enemy ship lining up for the shot, and he'll probably be able to guess pretty accurately where the shot will go and where it will be set to explode.
This is the reason why I thought the damage of the NC should decrease with increasing range, as well: The longer the shell has to travel the harder it is to set the timer so the shell will explode close to the target; in addition the target has more time for being unpredictable the longer it takes for the shot to connect.
Direct hits are (very, very close to) impossible this way, so the shells probably won't even have impact fuzes; even if they had they'd probably explode thousands of kilometres away from the target, anyway.
Notealso that the "skyscraper" ammo you mention is moving at almost the speed of light. Not an easy thing to track since the ranges are so close that the shot will get to you in less than a second. Assuming the target is at 150 cm, the farthest range of the NC and the equivalent of 150,000 km at a 1:1000 scale, the NC will reach you at little more than half a second.
That's far off topic, but my mind boggles trying to imagine accelerating a macroscopic mass (i.e. something you could touch) to relativistic speeds over just a few kilometres. I know it's 40k so it's probably just supposed to sound cool, but ... well.
I guess I should focus my mind elsewhere.

The NC rules for damage [...] are fine.
IMHO they're not. "Unreliable", yes. "Potentially griefing", just as well, at least if you (or your opponent) are unlucky. But "fine"? Not even close.
It's the way the process happens is the problem resulting in people bringing them en masse and so cry cheese. Make the NC more accurate and limit the number should be the way to go.
I made them more accurate and changed the process, yet you can't seem to get past how it's different. How's that supposed to make any sense?
I don't see the need to have to pick a ship or ordy. What is this for? To stay closer to normal weapon rules?
It's more for giving escort squadrons a slight edge, otherwise you'd be able to place the shot so it'd hit more than one from the start, at least if the scatter distance is short; with D3 damage against any ship touched by the template (LO shouldn't be much of a problem at higher ranges) this had the potential to go ugly pretty quickly for escorts.
Additionally I included it for the feeling that it's pretty much impossible to aim at "nothing". Space is black, empty and featureless, IMHO you shouldn't be able to just say "I want to hit that spot!" and your crew'd make it happen.
But, as with everything I posted, if it's generally disliked it's easy to throw overboard. I just thought I'd enter the brainstorming process by introducing something out of my head, as well.

The always scatters mentality is good but with the entire template being the hole it will almost always hit large base targets. That is something i'm not keen on.
It's the reason I somehow feel that the damage is still too high, but I don't want to neuter the weapon into uselessness, either.
Also it gives the impression of a moon sised explosion, which I really dislike.
If we want to talk realism we should forget the NC altogether. It just has too many problems in this area.

Let's just say that I can't really imagine what the explosion of an object traveling near the speed of light would look like (Crescent-shaped, maybe?

). I simply assumed that the template was a way to give the area of unpleasantness some tangibility in terms of game mechanics, not the depiction of a real event.
The damage 'potential' should remain at a max of 5 or 6 IMO, as it is a heavy hitter that should rival the potential damage of 6 torps.
The problem here still is reliability. If it is highly accurate you can't have it do this much damage per shot; if it's highly inaccurate it lacks the reliability it'd need to make the decision to brace an informed one.
See, if I have a 5+-armoured cruiser facing a wave of 6 torpedoes I can make a pretty good guess if I should brace or not: 2 damage is average, 1 and 3 have about the same, quite high probability, 0 and 4 less so, 5 and 6 are pretty improbable altogether. If the cruiser has already taken damage, if these torpedoes are not the only thing it'd be facing this ordnance phase or if the ship couldn't do anything useful next turn anyway I'd brace; if my (obviously pretty weak) plan depended on this cruiser being on LO next turn I'd take the chance and wouldn't brace.
If the same cruiser would be looking down the barrel of a NC I can't tell if I should brace or not. It could miss altogether, it could hit, but hardly scratch my shields, or it could cripple the cruiser.
To say it in mathematical terms: The bell curve of the NC's damage distribution is too flat and too wide to be any fun to play with or against IMHO.
Regarding the damage: With my proposal the NC would become more reliable, but as I said, it can't keep it's raw potential for damage per shot that way as this would make it too powerful, obviously.
"Damage potential" could mean anything, really; one type of weapon doing a single point of damage per turn over 10 turns, one doing 10 points of damage in one turn but taking 9 turns to get into position (or recharge, or missing 9 out of 10 times, or whatever), both would have done 10 points of damage in ten turns. So if we took away the damage potential of the NC but made it hit more reliably the weapon would stay a "heavy hitter" as it is now, wouldn't it?

The variance of potential damage through the range bands is a mistake which i made, it make NC's having long range damn near pointless.
It's not pointless, per se.
It could whack down a shield here, do a few points of damage there, generate blast markers, threatening tightly packed ships/making the enemy fleet spread out more, and of course you still had the option of concentrating fire if you had several NCs. Two or three hits, each doing D3 damage (LO shouldn't be a problem at that range), would mean trouble even for a battleship.
The closer you got the greater would the potential for mayhem become. It would be tougher to get the LO-bonus there, though, and especially the shortest band with the highest damage potential is easy to avoid; this would make the NC a bit harder to use, but more rewarding at the same time IMHO.