The expansys forums state that they themselves will honor any warrenty on the device.
I'm not too worried about lack of updates from HTC; Firstly 'cos they haven't been to quick in releasing them in the past, and secondly, that's why we're all here on XDA
Side note: Got mine yesterday. Loving it
Compaq iPAQ 3630 > HP iPAQ 2210 > HP iPAQ 6915 Mobile Messenger > HTC Universal > HTC TyTN > HTC Advantage x7500 > HTC Touch Diamond > Sony Ericsson Xperia X1 > HTC Touch HD
(Others: Samsung i600, HP iPAQ 514, HTC StarTrek)