Int/cateye is superior in every way to ammochain, in my opinion. Not only is ammochain basically pointless unless you're doing AoLT, but it blocks all the best traits.
I am totally waiting for the blast...(Yes I know it's your opinion, but I must refute it nonetheless!)
1) MAc pretty much makes Plasma builds possible (since even the Nuke Plasma Rifle is a little dodgy - since you often run out of bullets before finishing an encounter.)
2) MAc allows you to actually carry more...stuff, also allows you to carry spare weapons, mods and even a shotgun with ammo, (If you so choose) since you don't really need more than two stacks of 10mm/cells.
3) I agree it takes that MAc has the biggest effect in AoLT.
4) I fail to see how TaN, SoG and EE are the best traits in the game. I agree that EE is one of the best, but TaN and SoG...not so much. SoG simply because in a situation where you would build towards Ammochain, whyever you would use a pistol is beyond me. You still have access to Fin/WK/Jug which allow speed, which complements the spam provided by Ammochain.
5) I agree that Int/MCe is pretty good, but besides foresight, it gives little else. (On a more personal note, MCe confuses the hell out of me RE: knowing when enemies can fire
back.) Also, with MAc you can afford a few "probing bursts" into the distance with a chaingun to see what's what.
But anyway, back to OP...
Rapidfire builds are more suited towards single encounters as opposed to crowd control, as raekull said. Before getting MAc I personally just carry a shotgun with me, for crowd control. (Whether it is a vanilla shotty, a combat shotty or otherwise is down to RNG) Once you get MAc you can just corner shoot your heart out with a chaingun or something, since bullets REALLY aren't an issue anymore! :D (Which helps with "vision")