I am using nistune and love it. You do pay more when compared to a remap/socket-ed ECU. But the ease of tuning thought the diagnostic port has in itself proven more financially beneficial in the long run when going to my tuner and him being able to make quick adjustments and not charging me due to having to remove the ecu completly.
For the record, I am running 650cc Injectors (abit over kill), FPR, Splitfires, Z32, GCG Rb25 High flow (17psi), Cam Gears, 3" Zorst no cat, FMIC making a reliable 210rwKW.