I am back to a gut/poly hybrid after trying a full poly bed for a week (ouch!). I've been playing gut/poly for close to two years. Here's what I've found:
Tour Bite: Pros-spin, power; Cons-fades too fast. I LOVE this string, but I don't play it because it just doesn't last. I've got some Tour Bite Soft on the way to see how that works.
BH Blue Rough: really good! Tight at first but plays well--nice sound. Saws gut. This is my second fav, but I don't play it because it saws through the gut--even with copious use of string savers.
Cyclone: Feels like Hurricane Feel but more spin. Awesome sound. Nice hitting string. This would be my #1 if it would spin the ball a little more readily.
Hurricane Feel: Pros-solid feel, volleys, serve, durability; Cons-spin. Very good all around string.
Hepta-Twist: Pros-spin; Cons-can't stand plastic feel. Awesome string--very high spin but I can't get past the plasticy sound/feel.
RPM Blast: Pros-spin, power; Cons-horrible tension maint, kills arm when dead. This is the slipperiest string I have ever strung. Gobs of power and spin, but it is true what they say: it dies very quickly, and when it dies, it DIES.
Lux 4G: Pros-tension maint; Cons-average performer across the board. Average on all fronts except tension maintenance.
Co-Focus: Plays well, decent spin and okay power. Lasts forever.
I am currently trying Kirshbaum Pro Line II. I haven't hit with it enough to form an opinion yet.