I just got mine last week and I love it . With the wireless card and some SD memory, its like having a linux laptop in my pocket.
from what I can tell, everyone has problems syncing with linux OS is general. I haven't tried yet, because I am still playing with it on windows. Another thing - there area ton of open source projects out there like OpenZaurus and others which will replace the sharp OS on your 5600 - except, as of today I dont think any of them have a clean sync operation designed and built that works.
Sharp seems to have stopped supporting the device in anticipation of its new 6000 (which is BS, but what can you do).
But because it is linux, and there are a ton of fans of this device out there, there is still a ton of independent development going on.
they have a really active forum and incredibly helpful folks there. And check out the How-Tos and file servers there as well. This is where you will ge tthe most up-to-date report ont he state of the zaurus.