If you love to flash Roms and mods to your device it is always a good idea to have a stock image available for flashing incase you inadvertently flash something wrong or mess something up bricking your device. HTC has been pretty good about releasing source code and they have been pretty developer friendly especially with their developer edition devices. HTCDev recently uploaded the Stock RUU for the Developer Edition HTC One. The software version is 1.29.1540.16. If you happen to brick your device this provides a very easy way to get back to stock. This is also great for cleaning up your device in between rom flashes or after flashing several roms. Grab the RUU at the source link below.