Not wanting to be a troll and rain on peoples GM parade, but based on what I'm seeing with other brands transmissions these days, will parts for it be made available to transmission shops for repairs; or will GM follow the trend these days and only offer new complete transmissions for replacement. GM isn't the only brand I'm worried about, Chrysler too has a 8 speeds in certain products.
The reason I'm concerned is because of the experience of a Mini buyer up here. She had just over 100,000 kms (60,000 miles) when her tranny went south. She took it to a transmission shop who told her BMW wasn't providing any parts. BMW was willing to sell her a new transmission at $7,500.00 + $4,000 in installation and taxes.
The more cogs, gears and belts, the more to go wrong and based on my experience with my 96 Bonnevilles transmission (which was only a 4 sp), it will.
Again, I'm just saying this as towing does put more stress on a tranny and towing could be, and has been considered abuse by a manufacturer trying to get out of a warranty claim.