I've gotten some emails from old friends and VFP developers where the sender is asking me which version is best to upgrade a legacy application. Some folks are worried that the "newness" of VFP9 may make it a less stable upgrade whereas VFP8 has had a service pack and been around a while.
So far, it appears that customer reported bugs for VFP9 are 70% less in the same post-RTM timeframe than VFP8 bugs. And we have had roughly the same amount of beta testers and early adopters between both versions.
The trick is that we had many more tools to ferret out weaknesses in the core code of VFP for the VFP 9 release than ever before. Even with the huge changes to reports and the SQL engine, we had test coverage that could find almost any hole in the application.
To me, clearly, VFP9 is the way to go. I have no reservations in saying that this version of VFP is by far the most stable ever released.