I just traded my 370Z sports/touring/MT last week for an '08' Cayman S. I got a great deal on the S and a good price for my Z.
I haven't had the opportunity to take out the S yet for a good run but it is a nice car. The sound of the engine behind your head negates the desire to turn on the radio. The engine is extremely smooth all the way to the red line. True it's a little smoother over the bumps but mine is on 18" rubber, for now.
If you shop around there are leftover new '08' S models for $47000 with little to no options. So, it might only be a $10k stretch from a loaded MT 370Z to the '08' Cayman S. Of course you'd need to add an additional $1500 for a limited slip in the Cayman S. Three years post purchase you might get half of that delta back in resale value.
On the other hand there's a lot to be said for taking a 370Z with the extra $10k and seeing what pops out the other side.
