The XS Power seems much stronger (read: earlier) to me. It has a lower RG and higher RG DIff for greater flare. The TR is much more of a control ball for the average hand.Excellent for true medium oil, polish it for medium-light.
The XS Power can be a control ball for high speed players. It seems more, in its stock surface, for medium+ to almost medium-heavy oil.
This is besides the fact that the TR is all cover and core, while the XSP has filler in it. (That's not a knock on the ball, as their balls with filler are just used to make a less expensive ball with all the hitting power LM/L is knownn for: See Sure Strike and Counter Strike.)
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"None are so blind as those who will not see."