I agree with Rob, Ken helped me out quite a bit. I ended up going with DirectScan only because it was the first one to come up on the used market, and I was anxious to tune. If my $Free.99 laptop had been enough to run version 3 of TurboLink reliably, you bet I would've waited for it. The demo was awesome, and the 1.2 data frames per second didn't bother me. DS is borderline overload. If I only made ONE full throttle run on TL, it may not have been enough, but what fun is it just making ONE run???
I personally will always go with a laptop based scantool, I'm a nerd about getting as much info as I can. I understand the convenience of a ScanMaster, but if there's even the slightest change in my car's behavior, it'll probably be found by DS or TL.
BTW BOOST SENSING on TurboLink must be pretty awesome. That's one thing that'd be VERY nice to have.