The two racquets I use the most these days are the good ol' ProStaff 6.1 Classic and the Prince NXG mid. I just popped a string in a 6.1 yesterday and I'm kind of psyched because I've been curious to try a hybrid with especially loose kevlar in the mains (probably syn. gut crosses). Since I string my own bats, this isn't a very tough experiment for me and if I use it today, I'll let you know how it turns out. BTW, I usually use a 17 ga. syn. gut in my ProStaffs right up to 65 lbs. Not the greatest durability with this setup, but I really like the touch and at least what I perceive to be better bite on the ball.
The NXG mid is a lot different in comparison with the ProStaff - very flexible, smaller head, dense string pattern, and actually a touch heavier. The spin production I get with this frame, believe it or not, is at least as good as with the Wilson (must be the extra flex?) and I string these with either that same 17 ga. syn. gut or a multifiber of the same gauge. Not a lot of string movement and I think that this helps with the lifespan of the stingbed, but I wouldn't want a similar dense layout in a stiffer racquet like the 6.1 - I'd expect that to be way too clunky. If you sample anything with a dense stringbed, I'd recommend that it also has more flex.