I upgraded my Axim X50v to N800 and I do like N800 much more (my wife has my old x50v now). I can understand though that if you need mostly PIM, then X50v or any WinMobile based device would be a better choice.

I do have an extended battery for X50v and in my experience battery life in N800 with wifi on is much better than on X50v even with extended battery. However it is not too important for me because I did not see much point in enabling wifi on x50v - browsers available for x50v just suck and I did not bother trying to surf on x50v most of the time.

Over the 3 years I used my X50v I bought a few application, but all the functionality I got is available for free on Maemo: omweather lets me download/preview weather, maemo browser is way better than commercial opera, and maemo interface does not need third-party desktop managers I had to buy for x50v to hide ugliness of WinMobile. I never could find a free map software for WinMobile such as MaemoMapper and I could not justify wasting $200+ for mapping software I do not really need that much. I never could find an email client for WinMobile which could connect to my home IMAP server where I have a couple dozen of folders with few thousand messages in each, and claws mail on maemo does it just fine.

Bottom line is - you like WinMobile device - go for it, but there is no point in trying to convince it is better for everyone. We have been there, done that and know that it is not for us.