After so many rich and deep replies I watched “grandmaster test” aka Bryan Liles video “TATFT: 'The Layman’s Guide” (http://aac2009.confreaks.com/07-feb-2009-13-30-tatft-the-laymans-guide-bryan-liles.html) again and it not only reminded me to test all the * time but also to go for RSpec, Cucumber and Shoulda. So I think that’s it, as far as for me.
Considering the diversity and some contrary posts here, I can only draw the conclusion that one have to go through all the stuff out there to get a clear choice possible. So don’t get it personal if my choice doesn’t fit you, but I don’t have the time for checkin’ all the testing frameworks out there.
Thanks for sharing your experience. And don’t forget to test! 
Chris