Fun game world - I like it.
your analysis is a bit frightening for me ... I just realized, that the powergamer in our group chose the probably deadliest ranged weapon in the game... I just shouldn't wonder about that.
Yeah... and the melee equivalent is also pretty powerful (knives, which pull off the same tricks with less feats and less financial investment in ammo). On the whole, though, I'd be suspicious of anything which a powergamer picks.
EDIT: On redoing the numbers analysis above with reference to the actual rulebooks, I do become increasingly tempted to suggest a homebrew bow nerf or two. (Bows and arrows can only penetrate armour at point blank range in real life, for instance, so halving their AP outside close quarters would be fair; nerfing base arrow - but not bolt - damage or the boost from the Deadshot stance is also tempting, but I wouldn't want to go too far).