I owned both, both shot well, I kept the Bushmaster because it was lighter and better for calling, the RRA was a heavy barrel that did not suit my needs any more, and my buddy bugged the crap out me to sell it to him,but it is an exceptional rifle..
I have an RRA ATH and a Bushmaster .450. Both are great rifles and shoot sub moa. Hard to compare since they are different calibers and are used for different purposes, but I love em both.
A buddy of mine has the 24" Bushmaster Varminter. I sure like it. With 50 grain bullets it shoots like a laser and I don't think the weight is too outrageous. The 20" Bushy is the Predator with a 1/8 twist. I've thought long and hard about that one too. RRA makes a real good rifle but I like the Bushy barrels on the Varminter and the Predator.
Recently acquired a Rock River Arms Coyote Carbine (AR1542X).
Had a chrome bolt and trigger installed.
A4 upper with TRO standard handguard.
BCM GunFighter Comp. installed.
EOTech sight.
Function & accuracy is excellent.