My R700 is getting the full treatment at the 'smith right now, and I messed around with a lot of stocks in the shop, some on built rifles and some without actions. I didn't get to shoot any of them, but I spent enough time on them I don't think it would have changed my purchase. At the start, I was torn between the AG Alpine, the Grayboe Phoenix, and the Mesa Altitude.
I can tell you they're all amazing feeling stocks, and you really wouldn't be disappointed with the quality of either brand you're considering.
If weight is an issue, look at the Grayboe Phoenix, not the Ridgeback. It's only 32 oz and it is super nice. For reference, the AG Adj Hunter is 40oz.