I agree with you in liking UIQ more than WinCE, but it is just an interface layer that runs on Symbian, so any difference to other Symbian phones is probably because they were using S60 (Nokia). I never had strong feelings between UIQ and S60, so the advantages of a unified Symbian interface might be worth the loss. Nokia developer support for S60 had been improving up to the big Symbian announcement, although I haven't really been dealing with them since then.
I also gave up on WinCE about two years ago. At the time, none of the devices I could find even had an off switch. As a developer, if I left one of them in the desk for a week, it needed to be plugged in and have the time and date reset to be used again. Who builds a battery-powered device with no off switch? I assume that has been fixed by now, but what a mess.