Mine has been running fine off of 800 watts in 2.6 cubes at 32hz for over a year now, I pound the hell out of it daily. Used to have 2, the other is still bangin in my friends jeep off 750 watts sealed.
If you really want to know the limits of the type r see if you can get ahold of tommyk or sblazer. They were sending the r's gobs of power.
Also see the "Official Type R thread"
It has been known that the R is not really a great fart woofer at higher frequencies, tune low to mid 30's and burp mid forties for some good scores with the type r. phatty low end. Good size box for a 12 would be 2.5-3 cubes.