I can tell you this. I rebarrelled my RM to a 7.5 twist. I'm shooting 195 Bergers at 2950 and they are making bughole groups. (It is a 29" tube)
I just think it matters if you want to buy a new gun, rebarrel an old gun, or if you are ok with shooting 168 gr boolits. The RM has the same muscle as the PRC when they have the same twist. If you simply want more uumph, look at a 28 Nosler, 7 RUM or like someone else said a STW. There are other options like a 7-300 WM, 7-300 Norma, and numerous other wildcats to push faster.
I wanted something that would send the heavies at 2900 fps+, and didn't want to buy new brass and dies. The RM was the ticket for me.
Hope this is helpful.