Well, it's no contest, the gut/poly hybrid wins the spin potential battle big time. I have two matched and modified PSGTs, one full VS Touch at 55, the other VS Touch/PHT at 55/51. Have had a few hitting sessions with both. Last night was with members of my men's team one of whom is a giant who hits with extraordinary pace. Spin is mostly technique and I can certainly generate topspin with homogeneous stringbeds in a variety of frames. And I can hit very respectable topspin ground strokes and serves with full gut. In fact, full gut provides a welcome power boost for hitting penetrating topspin shots. But sometimes your timing is off and you want to come through th ball a little more. That's when the extra spin potential of gut/poly really shines. Even without perfect timing and tremendous RHS you still get huge RPMs which dramatically increase your margin for error. And the difference in spin potential isn't marginal. Switching from full gut to the gut/poly hybrid sent a number of balls into the net. Depth also suffered initially upon switching frames due to the tremendous difference in spin access. But once I reset my strokes that extra margin of error made a huge difference in consistency, especially when hitting with more pace. As a side note if you ever commit to a given frame I strongly recommend that you buy at least two and match them. It's a wonderful way to compare string setups with great accuracy (I have a third PSGT inbound from TW...two will be strung the same way and used for match play while the third will serve as a test bed for fun).