Honest opinion, what ROM for my Zaurus?
He he! If you manage to find any user pretending to have an honest (i.e. not passionate) opinion on this subject, you can consider yourself very lucky!
More seriously, there aren't yet many choices except if you're a die-hard beta-tester. The 1000 is still in its infancy. By chance, it's very similar to the 3000, which is a bit older, but there's no "stable" alternative ROM for either model, only work-in-progress.
All in all, in addition to the Sharp original ROM, there is (or will be in the near future) the Cacko ROM (Sharp-based), the OpenZaurus ROM (Opie-based), and I think you can probably install Debian as well (didn't try that one, I suspect the install to be longer or more difficult than the two other ROMs)
A good search on these forums should get you started...
Do we have any pages where you can see ROMS vs Model with pro's and con's of each?
I don't think that such a page exist, but if you do test many different ROM, please feel free to contribute by setting up a page with your opinion and the pros and cons!
If I reflash my shirtpocket supplied ROM, their manual makes it sound like I'll lose their conversion forever :-( Is this true? Or is there a way back if I don't like the uncharted territory of another ROM?
I don't have a 1000, only a 3000, but given that the 1000 has a (limited) flashROM to hold everything, I expect a NAND backup to be a good solution for a later restore if you miss the original ROM? I'm sure many knowledgeable users of this forum can confirm or infirm this...
All in all, I think that in a few weeks/months from now you will have plenty of alternatives even if you don't feel like "exploring uncharted territories". Right now, it's "living on the egde", though!