well, hes right about getting the valvebody one installed. once its installed, you need a new valve body if you wanna take it out. just part of the nature.
supposedly as long as he gets the right computer code, it should be fine, but you can get a chip to firm up the shifts and it will be the same as the electronic shift kits, plus the chip will give you some hp if you advance the timing.
valve body kits are easier on the tranny though. they let the pressure be a specific amount that doesnt cause damage. the electronic ones just raise the pressure in the valve body and it can damage the tranny if improperly tuned or if you have too much fluid or other things.
all things being equal, i would goto another tranny shop and get a valve body kit put in. and it will be better for you.
**I have sigs turned off, so if you're asking for advice based on your mods, I can't see them**