Ok, let's see who's going to hit me on the head.

Imagine that i want mobile internet, a good PIM that syncs with Outlook/Gmail, an outliner.
Imagine i do nothing with music or video (yes, i'm the only person that knows that internet exists and doesn't have MP3's on his PC).
Imagine that i just want things to work and i love being root, but not on a device that i'm relying on for work and personal use.

Apart from losing a fairly decent browser, what do i lose when i switch from my N800 to the BlackBerry?

Ton.