I'm not going to say I'm the best at AoMr, but it's been my favorite game mode since before it *was* a game mode. I have beaten AoMr on HMP, and that was with no special pistols spawning. Which is really my point - I got through that game with 2 speed-loader pistols. I also never ran out of ammo, and never *do* in AoMr type games. I just take about 6 full stacks with me at all times, with some replaced by ammo chains (that I just unload), if I find them. 10mm ammo isn't common in Hell, but 600 rounds has always gotten me through. Also, I'm not sure what pistol build *wouldn't* get SoaG3. Personally, I find the benefits of Gun Kata, well, not that great. Between cover, reloading only 1 pistol, and the benefits of the speedloader, I tend to always go for SoaG3, DG, EE1, and then add in levels of Fin or SoaB. I just go for maxed damage per second and per shot. For 7 feats, 2 speed-loaders would out-dps blaster + sharpshooter, unless it's on very high armor enemies, I'm pretty sure.
Let's math it up. Blaster average damage is 19 at a speed of .32/shot.
Dual Speed-loaders with SoaG3, DG, Fin1, EE1, and SoaB1 would be 18 with about the same speed. Huh. Alright, you're right. Now. You're going to be weaker at all points up to level 7, even with the blaster, though. Now, Trigun, yeah. That'll go in favor of Sharpshooter. Good luck finding it, I suppose. I've found, when doing AoMr runs, 2 blasters and a Grammaton (edit: Since starting playing 9.9.4. So, about 25-30 games). So... if you get a special pistol or take 10 feats towards Whizkid to make one (and find the rare mod to make anything better than a speedloader)... Then, yeah, that'll outdamage dualgunner without similar advantages. If you find 2 rare pistols, though, dualgunner probably then wins out.