I got told it had to be cold as well, but TT insists it should be warm so that all the contaminants are in suspension, otherwise you risk leaving it in the gearbox. Its also not a reset, its a re-adaption of the basic settings, so nothing is done with the map on the DSG ECU it just goes through the process of re-learning the clutch bite points gearchange points etc etc. So Revo software wont be affected, hence you can do the adaptation yourself with VCDS.