If Leapers stocks are cut from the same cloth as their scopes I'd definitely pass and stick with RRA.
The Rock River will cost a little more now, but you'll only cry once. The Leapers stock will probably cost you more in the long run, because once it fails you'll end up buying the RRA anyway.
Come to think of it, are the Leapers stocks the same cheap, Chinese knockoffs that were selling on eBay earlier in the year, just prior to eBay banning the sale of AR parts? If so I'd avoid them like the freaking plague. In May I helped a friend try to install one on his Bushy carbine. The buffer tube actually bent when I tried to torque it down. Considering that the bolt and carrier travel at very high speed in that tube (right next to your face) I wouldn't suggest that you cut corners.