Hang on a second.. what RB25? R33 RB25's can't be NIStuned easily, you need either a Z32 ECU or an RB20 ECU + window switch for VCT.
R34 RB25 can be NIStuned very easily.
As said, pick a tuner and go with what he is comfortable with. In our state, there is no shortgage of good NIStune tuners.
Also, if you think monitoring engine vitals is handy then do what I do with NIStuned and stock ECU's.. I run a carpc with Datascan and a consult cable permanently hooked up, infinitely superior to a little LCD screen.