The regedit tweak doesn't work at all on this phone. At least that's what every other thread covering this topic in this forum and elsewhere has concluded. It's been my own experience as well. It seems for some reason HTC REALLY thought we should have screens that light up when we receive SMS and that we shouldn't be able to change it. This was also my experience with the TP1 and the XV6700. It never made much sense since it clearly aggrivates users and doesn't reflect well on HTC or the carrier when battery life winds up being half that advertised (at least on phones belonging to people with texty girlfriends).
If anyone is running a custom ROM, I'd love to know if they made this problem go away. If so, then somewhere in that ROM is your answer.
