I owned the Ultimate 1 before purchasing the 2 recently. It's still relatively new with maybe 50 hours on it and I've not yet installed my NOS Telefunkens so these are early impressions.
It does seem to be slightly more full bodied and a tad warmer with a bit more meat on the bones. I don't think the change is all that huge and if you ask Ken he'll probably admit as much. If you're happy with the Mk1, save your money or spend it on vinyl. Also, NOS tubes will make a much bigger improvement than upgrading from Mk1 to Mk2!
