The RX7 is definitely a faster all-around car than the ITR stock vs stock with same driver. But finding a well taken care RX7 is hard, even if it's stock, the motor requires a rebuild after a relatively low mileage (includes all seals and vacuum hoses).

Don't assume that the ones taken care by the dealer would be "ok". Those are the worst since there's almost NO qualified mechanics who could work on a rotary engine. 7 owners always say, if an RX7 is brought into the dealer for major service, it would most likely die there.

All information is according to my friend, who owned an FD and is the admin of the 7 forum so his source is pretty reliable.
http://www.rx7club.com/