My user name is actually Miata spelled backwards. 

   I currently have three Miatas and one 2000 Boxster S.    One Miata is track only, but is still street legal, one is tubro'd and one is a parts car for the track car.  
I've auto'xed both and its night and day between them.  Boxster is like riding in a well behaved sports car where as the Miata is like a gocart on steriods or HGH.  Race, well thats easy, the Miata.  I'm too cheap to race the Boxster as often as I race the Miata.
 If I had to choose which one to drive, if was longer than 2 hours, the Boxster, less than two hours and wanted to "hang it out" the turbo Miata.