Like many others, I have been holding off on taking the Lion plunge from Snow Leopard, primarily because of lack of Quicken (i.e., Rosetta) compatibility. I have used quicken continuously since 1991, and didn't want to go through the nightmare of switching to another product or relinquishing features such as making payment from within the program. Depsite the many annoying idiosyncrasies and minor "bugs" with Quicken over the years, I have learned to accept them and have generally been happy with Quicken (although I would have liked to see updates beyond 2007).
Now that Intuit has produced a Lion-compatible version of Quicken 2007, I was hopeful that I would be able to migrate to Lion, once my initial testing of the product demonstrated adequate functioning. I created a copy of my data file using Save A Copy... (I first reindexed the file using Command-Option-B). I then installed the Q2007S under Snow Leopard without difficulty, and it opened my data file without any problem, with all registers having the correct balance. The one-step update window font was a little different, as if smoothing wasn't being applied, but this I'm sure is a minor issue. I did, however, experience a crash during my first One-Step Update (where several differerent accounts in several different institutions are checked, including Chase, Amex, Schwab, and Wells Fargo). I submitted the crash report to Intuit, but haven't received a response from them yet. I reopened the file and tried another One-Step Update, which worked flawlessly. I had a few duplicated transactions redownloaded from a few accounts, but I deleted these, and now everything is working as before. I have made several online payments (through Wels Fargo), and these are working without a hitch. I added some new payees, as well, and this works, too.
My next step will be to try things out under the Lion OS on another, less mission critical computer (Mac Mini), before updating the OS on my main computer (Mac Pro). Hopefully, this will finally allow us to move to iCloud, which my wife and I will need, since we currently depend on MobileMe and share each other's contacts and calendars.
I will post updates as I move through this process.