I tell ya, this sync thing needs to work or it’s just a pain in the arse.
I’ve gotten rid of Plaxo because I had the same problem I had with Zimbra – it was silently deleting my data. As far as I can tell, if there were two “Home E-mail”s (or any type of contact point) for a contact, Plaxo would pick one to delete.
In addition, I had trouble with Plaxo creating lots of duplicates of my contacts. They helpfully offered a “remove duplicates” feature as a paid service, but if they didn’t duplicate the data in the first place I wouldn’t have had a need for that service (I didn’t use it).
I know I’ve lost some Address Book data because I used Plaxo for a while and have run into contacts I know I’m missing a specific e-mail address or phone number for, but I have no idea exactly how much I’ve lost or where. I’ll need to go through old backups and compare them to my current data. I guess the best way to do this is to export everything as in vcard format and use a diff tool. I’m not looking forward to that.
One thing that Plaxo did well was include a friendly uninstaller, especially since the Plaxo app seems to get placed somewhere other than the Applications folder. I didn’t actually discover where it was because the first hit in Spotlight for ‘plaxo’ was the uninstaller.
My data is important to me. If you’re a sync tool, you get one chance to work properly – fail and you lose my trust forever.