I never used them until the 2010 FAQ dropped the price. Before then it just didnt make sense for what you got. Since then I've used them in a few different fleets as alternatives to the dauntless to give a different style. They usually work best in pairs for the s16 web to a side. I also like pairing them with Lunars to boost battery strength and torpedoes while using the larger cruiser to block fire on the cl. S14 batteries and s8 torps are nice. On their own, two endeavor and one endurance is an alright squadron.
They aren't my first choice but I do like to swap for flavor and the extra turret is nice.
I don't much like the BFGR price, I get the prow is included but I like it as an option rather than included.