Debranding is not that hard. The way it is done is by using an official (unbranded) HTC released RUU. RUU's are Rom Upgrade Utilities. They come in the form of an .exe you run from a PC, with the phone connected in HTC sync mode.
Installing an unbranded RUU on an unbranded phone is really simple. HTC tech staff do this to repaired phones. Its literally plug in the phone and set to HTC sync and press and run the RUU. It does it all in 1 click. Since this is the official HTC way to do it, theres no real danger as its designed specifically for this purpose. The only problem would come if the cable was unplugged or power was lost during the operation.
Now it is a bit different if you want to run an unbranded RUU on a branded desire to debrand it. The phone has a CID (carrier identification number) which uniquely identifies it to the carrier / operator. When an RUU is run, it checks the CID on the phone to make sure it matches to the range of CIDs it expects to see. If it does not match, it aborts.
The CID can be spoofed and the RUU fooled and this is how debranding is done. This is done by making your SD card into what is known as a goldcard. There is a tool for this in the main sticky of this forum. There are also plenty of guiddes around to do this. Its not THAT straight forward of a process (its the hard bit) but its not amazingly difficult either.
I would suggest investigating this a little further yourself to be honest. You can make a gold cards in half an hour or less and you could debrand the phone yourself in little under an hour with the right instruction.
If you're up for the challenge, let us know and we can point you in the right direction.