I've run almost every possible build in the Adder. It's not as bad as people like to think, but it's not nearly as good as it should be either. I'm not saying it should be able to compete with the 'meta' lights, but unless you get a lucky shot off with your LBX20/gauss or are completely ignored for the majority of a match, you can't even go toe to toe with most other light mechs to begin with.
At the very least it should fill a niche of being a (comparatively) slow fire support light mech that can actually stand up to other light mechs if they decide to stick around and fight - That's the only reason you'd even sacrifice speed to begin with. But it doesn't.
Is it fun? Yes.
Is it bad? Sort of.
Should it be better? Hopefully no 50% ER PPC heat reduction quirks coming in, but yes. Yes it should.
Splatter?
ADR-B Can swap 2 6's for 4's, or go all 4's for that much better accuracy/ammo efficiency. This is not a brawler and needs to be played like a splatcat made of wet paper, personally I set torso mounts to group 2, arms to 1 and fire them both if the opportunity arises, for faster moving targets or quick shots as I'm turning I'll fire the arms first as they track much faster.
My favorite build so far:
ADR-B
Obviously, both builds can be done on any Adder... Like any build on it.
Increased ballistic ammo/ton would be an amazing quirk. I'd also be fully willing to spend a million c-bills on a head that does not have a flamer in it, even if you lose the weapon mount altogether, coming with a hard locked clan active probe would be acceptable as well.