Not sure I'd consider the Milwaukee an upgrade from IR as far as ratchets go, and that coming from a Milwaukee fan.. the new fuel models are larger than the old. I'd spend some time on YouTube and make a decision on your own.
Milwaukee's big advantage is the vast system of tools that come with the platform. To single out the ratchet alone against IR, and you already own IR, I'd dunno.. doesn't IR have a 12v 3/8"?.. and they have the cordless hammerheads too... not sure if you'd really be gaining anything.. check torque specs, and do size comparisons..
Yea man, you can get the whole 12v IR kit with battery and charger for $170, and that's not even shopping around..
Rated at 30ftlb but that might be an honest spec.. the head on the new fuel model is bigger, and the original Milwaukee is probably as powerful as that 12v IR.
20v 3/8 says 54ftlb.. again, the IR head looks smaller
Here's a vid showing old vs new..
Updated (better vid)
Yea, tough call. u have nothing to loose trying the Milwaukee. If nothing else at least you can get some other m12 stuff too if you ever wanted.. I'd definately own those cordless hammerheads from IR if I was a pro mechanic though. The bare tool for the 12v IR 3/8 is only like $120 though.
