Thanks for the information, but I don't think it's entirely accurate. Those with older phones (that haven't taken updates from HTC) will possibly have the old radio firmware. And if you are S-ON and HBOOT1.5, there's no way to 'get' the new firmware on the phone if you are unlocked.
So you must get the updated radio firmware (1216), put in in the root, relock the phone, and do a bootloader boot to flash the radio firmware. Unlock again, and then you are good to go. I had the 8xx version radio firmware and couldn't run any newer ROMS with working wifi until I got the updated firmware.
Be advised that lock/unlocking wipes your phone.