Glad to hear you're sticking with 18x20. I've hit with the Pure Storm and there is no comparison to the great PSL! It felt like a toy. Forget it.
Regarding power, you can always get more by lowering your string tension. For me the absolutely only thing that could possibly make the PSL even better is increasing the stiffness a bit. So I've ordered a custom frame from Vantage Tennis with the exact same specs as the PSL except for a stiffness factor of 70. Should be here next week. Will report on how it goes.