Saw both in action over the weekend at a LR match. Both .308's. The Stealth was actually my .308 savage 10FPSR in a LSS chassis but it's effectively identical and it's been worked over and trued. Both were plenty accurate shooting hand loads. Mine were 168's, his were 175's.
The RPR butt stock certainly looked to have more adjustment capability and a cooler look but it (the rifle) was also bulky and seemed to require a lot of effort on the bolt to strip a round and chamber it compared to the savage/LSS setup with AI mags.
I'm personally not a fan of long AR style barrel shrouds on a bolt gun. They usually get in the way of a nice low scope mount. The RPR is no exception on that point however the design of the RPR brings the bolt up relative to the head position by almost an inch which means you don't need such a tall cheek piece off the stock attachment tube like you do on the Stealth and you don't have to shoot from such a tall head up position which for my money is a more comfortable shooting position to be in.
If I were to buy a Stealth today I'd expect more or less what I currently have. An accurized Savage in a nice chassis stock. If I were to buy a ruger I'd expect some ergonomic improvements over the Savage but an equal number of things that swing the other direction.
All in all, I'd take an out of the box Stealth over an out of the box RPR but I'd wish for a few minutes that the Stealth had been designed to be what it is rather than adapted to be. The RPR is at least designed to be what it is and carries that off pretty well.