I have just switched to a hybrid of poly mains (Prince Tour XC 15) and syn gut crosses (Prince Syn Gut 16) in a EXO3 Tour 100 @ 52/56 lbs.
Had been playing with a fullbed of Prince Premier Attack (multi) ~ 60 lbs.
Will say that I feel like the switch is noticable, and in a good way. Generally have more bite on the ball. I will hit mainly topspin shots, flattening out for attempted winners, and at least after 4 hours of play with the new hybrid spin seems much more accessible than it has in the past. I'm also noticing my topspin and slice serves have more movement on them, and I can place them in safer spots above the net comfortable they will dip in for a solid second serve option.
I haven't played with a fullbed of poly yet, but based on the general reviews I think I'll stick with a hybrid. I definitely don't feel there has been a lack of touch/feel with the syngut crosses, and my arm/elbow haven't complained one bit so far.
At this point my plan is to continue with the hybrid setup, and the cost effectiveness of the syngut cross helps keep spending lower per racquet. I'll probably try a couple different polys as well as mutlis for the crosses (NXT comes to mind).
In short--highly recommend this setup. My progression : Full Syn Gut > Full Multi > Poly/Syn hybrid @ lower tension.
Good luck!