RCG's analogy with the armageddon gun is faulty
it confounds effect of numerical power with effect of power of potency
you can always compensate for less power of potency with numbers but this doesn't change power of potency, or simply power.
a weapon's power remains its ability to inflict damage when a hit occur.
a 44 magnum is more powerful than a 22. a BC is more powerful than a lance. naturally if a weapon doesn't shoot or doesn't shoot as often make it less effective. but not less powerful.
(btw, funny that in post 158 RCG then agree the BC is individually more powerful than the lance, but also less reliable)
in addition, other than planetary fortresses and stations, most planetary defenses have only one hit so the BC's ability to inflict criticals make it no more effective than batteries. and as for fortresses and stations, marines should not be taking them head on so i see no reason why marines should have BCs for planetary assault either. The BC ability to cause criticals make it an anti-capital ship weapon, which is not the role of SM, as well as compete with what SM should be doing, which is deliver SM for hit and run attacks.
i maintain that if you to review the Space Marine list without prejudice, then a consideration should be given to taking away the BC and giving them something else, whether that be prow LFR batteries or a single lance (possibly 2) for the strike cruiser. in so doing, would you more likely apply the SC against line cruisers? would it be less effective in delivering marines? would it be unfluffy? my answers to all is a "No."
Re: Dauntless vs Strike cruise comparisons, this is valid not just from a class and displacement argument but also from mission perspective.
imperial line cruisers are meant to engage enemy ships in battle, especially enemy capital ships.
dauntless are meant to patrol and take out escorts rather enemy capital ships. in this regard the strike cruiser is similar.
that strike cruisers is the only cruiser marines has doesn't mean it shouldn't have a defined mission (delivery of marines and patrol, should be able to take on escorts) or be applied outside its mission design with reliable success (against line cruisers).
out of curiosity, which do you all think is better in a one on one fight, a strike cruiser with 2 shields at 160 points vs a lunar at 180 points?