i would suggest you use a kernel patcher/bios loader with live blocking (so that in the even that something went wrong and you tried to access live with a hacked bios, it wouldn't let you.)
other than that, it appears to be that MS is not scanning hard drives at this time and so it really isn't a risk cold booting. (realize that theoretically, they could start scanning drives whenever though and in that case, you could get banned...that's where the potential risk comes in)
the hard drive marriage theory still applies however, so you should read up on that a little bit. (basically, once you sign onto live, you can't change your hard drive without getting a new eeprom).