I have two of the 5-25x56's with the Gen II-XR reticle - use them for long range tactical shooting out to 1000 yards. One is an earlier model, without the parallax marking, and one is a newer one with it. Haven't had any issues with either one, although some people did have oddities with the earlier ones. In many cases, the parallax would stop working, but that could be tracked back to the rings being tightened beyond spec, and loosening them would free up the parallax.
There was a $1000 difference between the PR and S&B at the time I bought them, and having used the S&B, didn't feel there was any benefit to them other than history. I do like the knobs on the PR more, with the milestone setup, however. I also have USO SN-3 scopes, which I think are absolutely awesome also. The ability to customize them to the nth degree is a huge draw - illuminated or not, left-hand windage, different knobs/reticles/tube diameters/objective sizes/etc.
When you're talking about scopes in this range, you really can't go wrong. Just find the one with the features that suit you, try to spend some time behind the various models, and go from there...