I know this topic is old, but 2 yrs ago I had this same question. Now I asked my local dealer (not big stores like gander mt or dicks) about a bushmaster predator. He looked me in the eye, turned around and grab two catalogs. One was the bushmaster catalog and the other RRA, he said I'll show you this bushmaster and the price, but Im going to recommend an RRA. He also pulled out a list of people who shoot these in the area for competitions. EVERY winner was an RRA, and bought from him, most dealers in the area don't deal with Rock River because they don't make a production gun.
Now he had a few guys buy bushmasters from him which was mostly for hunting. If you were to buy one remember this, bushmaster rifles are a production gun. All the ones who had problems had to be send them back to the company.
RRA has models, but every little option is your specific pick. Right now they have contracts with DEA and FBI and some of the tactical equipment is hard to get. Sporter rifles seem to come in shorter time. I waited almost 10 months to get mine which is a elite car a4 with a chrome lined barrel, but i love it! I didn't even pay the amount listed on the website for my gun. I haven't had 1 misfire or jam. CHEAP factory loads shoot 1in or smaller groups. I'm in the process of working up a load with 55gr bullets.
IMO RRA is the best, now my question for you is-what do you mean by availability of parts? I haven't needed anything as of yet. Hopefully more people out there can give input on both, many people had the same feeling after somebody was elected and thinks they're evil.
