Well...I'm just having a few little niggles since PR 1.2 (touchscreen scrolling freezing on MB, random freezing of desktop apps) - before I reflash I considered trying one of these options...obviously will backup but was wondering whether Restore Original Settings overwrites PIM data - guess there's only one way to find out...

*edit*

OK, tried both (forced in part by the fact that I have no access to flashing till Monday, Mac OS X 10.4.11 is not supported by the flasher files it seems):

Restore Original Settings : The only thing I lost here was a contact shortcut on the desktop. And, for those having trouble with lost GPRS settings since 1.2 , this option restores them.

Device seems faster and smoother, no more lags or freezing.
Still, may well end up doing the reflash anyway...