Flashing the N1 with an HTC ROM is not a trivial thing - much more involved than jailbreaking an iPhone, for example, and I have never had a cooked version of Android that was stable enough to use every day (others seem to be OK but not in my experience).

I recently returned a Sony Ericsson X10 because of their horrible Android implementation and have ordered a Desire to take its place (until the new iPhone comes out, anyway). I became a fan of Sense on the Hero and am looking forward to the new version on the Desire.