Interesting points brought up here. Going through the different testimonials, I expect my car to be on the verge of oil temp induced limp modes at my next trackday.
My preference would be to swap the factory oil cooler for a more efficient core. STETT don't offer this possibility unless you replace the factory thermostat or delete it completely.
I wasn't keen on this, but as it seems their 180C thermostat is somewhat similar in range compared to the Euro spec thermostat. So this may be an option.
However I don't think the connections will be compatible to the AR OC I already have.
In this thread there are a few pics of the Dinan OC:
http://www.e90post.com/forums/showthread.php?t=528269
Looks huge compared to the tiny stock unit.