I went to the REI here in GSO and got four of those rings the other night. I haven't had a chance to try them out yet, though. Just by feel, I can tell they're lighter than my CC buckles.
I haven't had the issues with the buckles that you're reporting, really. I just don't ever tighten them down all the way. I think it might be a problem with my ULB though - you have to get an HH pretty tight or the ridgeline/bugnet sags all over you.
I'll definitely try out the rings, and I may switch over. Since I've already got my support cord tied with two bights, it won't be hard. Basically just directly sub the rings for the buckle.
I think I'll keep using the separate straps, though. With my "blackbishop's sack", you kinda have to take one off anyway. And it's not a big hassle for setup. Pretty quick and easy, actually. Plus those 'biners are fairly expensive, and I think I'd gain more weight using the rings AND 'biners than I've got now with the buckles.
"Physics is the only true science. All else is stamp collecting." - J. J. Thompson