Definitely do Autocal. That way when you get built trans or need your tunes updated Nick can just email you the tune file and you're set. Instead of having to send your ECM to Nick everytime. Like Caleb said you can also read codes, datalog etc.
I have the V2 now which is nice but wish the Autocal was around when I first got EFI Live. But its nice cause I have switched through 4 different tuners so switching tunes was effortless.
04.5 GMC CCSB LLY - Code name- PPRWT - Built Motor, Built Trans, Big Twins, Dual CP3, etc - HSP l Industrial l LDS l Burkette Racing l Danville l Suncoast l Socal l Bullsye
05 Chevrolet CCSB LLY - ADII, Profab EGR delete, 4" exhaust, Built trans