Now, now... Symbian doesn't suck.
We did some development for it a while ago (on the Nokia 9210). And yes, I can say forst-hand that the Symbian consortium has been bad about provding information to developers. But despite the (mostly organizational) flaws, in some ways Symbian is a nicer OS than WinCE/PocketPC. For instance in dealing with low-memory (= low-cost) platforms, in providing snappy user response or in having long figured out all the phone things that only recently have been done somewhat right on the XDA (volumes, ringtones, sms, etc.)
Anyway: OS-wars are sooooo nineties. A true hacker can do his magic independent of the underlying OS, and only those that know they can never master more than one OS will fight to defend theirs.
And yes: I'm getting an XDA-II. I wouldn't want the P800 as a PDA. But to be honest, there have been times in my life where the XDA has really sucked as a phone (not 100% reliable in signal aquisition, hangs sometimes), and the display does get smudged with ear-grease (or am I the only one...).