i agree, as a british car racer I can relate to the joy of running something different. However, at the end of the day it comes to track time. If you have a miata, I would run that thing all day long. You know they thing will always run, easy parts to get, and loads of fellow competitors.
I can also relate to the problem. I have twice had a driveshaft blow apart on me in a TR7. Not as much damage as you got, but did have to pull the tranny out because the bell housing was cracked up. No other damage, but I will never forget the sound when they blew. I was like someone on the side of the track shot a cannon at me.