All I know is, that since going to WM 6.5 I have not looked back. For a device like the Touch Pro I've found the scrolling and menues in WM 6.5 to be far more touch friendly. For the ROMs I've used I've found WM 6.5 to be as stable as WM 6.1 if not more.
The only disadvantage to WM 6.5 for me, is that some software does not work well with it, given some software was not written for WM 6.5. But with the
new release of Pocket e-Sword working well with WM 6.5 I'm all good.