Upgrade from 2006 Premier to 2007 Deluxe?

Can't answer your specific question regarding Premier06 > Deluxe07.

Can comment on Deluxe > Basic - works fine and nothing blows up. Ran both Deluxe06 and Basic06 and swapped the data file-set back and forth from one machine to the other.

Recall a similar query in the Intuit Quicken forum in which author was 'downgrading' from H&B to lower version. An Intuit moderator chimed in with a comment as to what happens to account types unique to H&B - the account type for these was changed as I recall. Tried a quick search of that forum but couldn't find the thread - you might have better luck with a little more perserverance. Bottom line though, as I recall, was that nothing 'blows up' - there were certainly no dire warnings or sirens going off.