Lots of times the generic scan tools miss information or codes that can be stored in the OEM section of the PCM. It only reads the generic section.
Also with control area network in play these days , a generic scanner wont tell you anything about any other functions or codes stored by body modules or any othe type of module(nav,traction etc.)
Plus you wont have any bi directional testing of any devices.
It will give you a code for the engine or trans, and some wont give anything more than a p0700 for the trans , which can make a diagnostic on that a bit tougher.
I would look at the actron scanner. It can scan the generic and OEM section of most cars.
I have a Snap on MTG 2500 with all but the last upgrade. Its OK on older stuff. The shop Has a chinese made scanner called Launch X 431 , and it is the best bang for the buck out there. A comparable snap on would be over 20 grand. The wired version the shop has,was used, sold as new with full warranty, for 2000 bucks.
The launch X 431 is DA Bomb.
For 85 bucks, all included for a genric scanner, Meh, a hand held would be easier.JMHO
Fact is stranger than Fiction