Honest opinion ?
Yeah, dont take the dealers opinion as fact. Especially for something like a $3200 repair. Were you experiencing transmission problems ?
Get a written report from the dealer on why the transmission 'needs replacing'. There are many things that can go wrong with the MTX. Throwing the whole damn thing out is overkill. It's not like you are going to get a better trnsmission from them, only a newer one.
I dont mean to be harsh with you but it infuriates me that dealers and repair shops throw this stuff out without explaining things.
Good luck.