I did try to use that type of support at the 2014 RBL comp but found that it just was stable enough to maintain a fixed point of aim on a 1/2moa target @ 300 yards, the clamp did. With regards to fixing the clamp to varoius stock profiles/materials, I can confirm that I have used the clamp on a multitude of fore ends ranging from a No.4, Sauer 202, ACIS, Tikka T3 and varoius AR15's fitted with circular handguards and I'm happy to report that it worked on them all. I'll post a few pics showing a few examples when it eventually stops raining I get an opportunity to take them.
I'm quite sure that a section of picatinny rail used in conjunction with an adapter would work and offer a certain degree of support, just not in the same way and would certainly not achieve the same results.