I use a Tech II daily one thing that no one has said here is updates. Maybe no is aware of it here ,..it but most updates are downloads that ONLY deales can get. For instance you have a 02 Monte with a 0300 code ( misfire) you have to load the vin , hook up to Gm service download the correct update and then load it to the vehicle PCM. Same goes for the speed rating on tires and other itmes like that Hell even the remote entry on some models have to be downloaded fro the site. Lack of memory space on the Tech II.
Sorry after I posted I saw a post I missed about soft ware. You can get them and use them for your own use but they are others that Blow the tech II out of the water.. Snap-on tools if very nice I have used it and it works as well as the techII with out the draw backs other than price.
Things I have already purchased for upgrade:
20" wheels and tires
Diablo Preditor Programmer
Wood Dash Kit
Future Upgrades being considered:
-Volant Cool Air intack w/snockel
-Corsa Exhaust (already have one on my boat Crownline 225BR)
-Lowering Kit f2"/r3" (Ground Force $399 best price so far)
-Maybe Audio upgrades to Bose system. (not sure it is viable based on the difficulty to upgrade/replace Bose system and maintain steering wheel controls).