5/5, AC 2's are bad, ac 5's on the other hand... You want the extra armor. Besides heat generation is what makes less weapons more deadly. Two lasers should preform just as good as three and you have extra armor.
That's my current build, XL170 and 3 tons of ammo iirc. I like it, I like the AC on the Urbie. It's an Urbie afterall, all that laser-vomit doesn't make any sense. And it works fine.
Agreed, AC5 all the way. I ended up with Deathbugs build, but put one JJ in each side torso and 2 tons of AC5 amm in the CT. I got the extra JJ in by shedding armor from the left arm and three points from the head. It works great, far better than I expected it to.