Thanks for a good summary of the issues. I have deployed syncml on over 50 Palm Treos using the Synthesis utility against eGroupware's syncml capability, with pretty good results, except when it came to the clock changes, when calendar entries were often mucked about, especially recurring events. Syncml, as a piece of the building blocks that make up the service, may or may not have been to blame, but that was the one flaw that made syncing calendars fairly tense twice a year. Hunting down the issue, whether it was on the Palms, the Synthesis syncml client, the syncml code on eGroupware or the eGroupware calendar was a nightmare, never fully resolved.
But the deployment itself was extremely trivial, that's for sure.