TurboLink is a good scan tool, couple it with it's exclusive boost sensing hardware and it's a great scan tool.
Being able to record all the sensor data as well as boost and how it relates to the other sensor data is a big plus, at the track and for diagnostics. Being able to review pre and post change data files is invaluable.
Scanmaster is ideal for daily driving but it won't be long before you'll want to dig a little deeper than Min O2's, Max KR and their associated MPH's. Especially for diagnostics and certainly at the track.
A big advantage of TLink is it's portability. Record a pass in your car, move it to your buddies GN and record his pass - compare the data files in the pits. I have track and diagnostic data files from 2 GN's in addition to mine on my hard drive. The comparison is always interesting.
The slower frame rate has it's limitations, and the faster you go at the track the more limiting it becomes. There can be times when you have some weird problem that is random and brief and TLink will have a tough time capturing it.
My needs have changed so I'm moving to Direct Scan, but I have used TLink since May of 1997, and it has served me well. It was once said that TLink is sufficient for 90% of the TR's out there, I think that's about right.