Hi thanx for sharing...
The while I undestand the fuzz about the sunlight... I think people is axagerating. The last thing I've think to do while standing under direct sunlight, by any stretch of the imagination, is to watch a video (the only time I'd be worried about display quality) on a ZuneHD or for that matter any portable display. (how much power a device has to emit to be remotely comparable to the sun's output, anyway?!)
Actually your test about you being able to reliably tapping the screen and finding the spots without looking, is far more close to real use (at least for me).
BTW, I learned about the XNA update for the ZuneHD... I am a developer so I feel even more tempted.