Can you use W8 upgrade key off 8.1 preview?

[CurrentlyPissed]

I ask because in toms review they state "Upgrades become full versions", and how MS states it was a mistake to ever do that.

So if you have a windows 8 Pro upgrade key can you bounce off the 8.1 consumer preview with your 8 upgrade key? Or will it still require a full version key?

Also is there a difference between activation on a preview, and RTM? If so where do you go to get the RTM?

Thanks in advance.