A question brought up earlier was about trans temp not using tow mode. I have the Bully Dog tuner that displays trans temp, exhaust temp, intake temp, average fuel consumption, current fuel consuption, turbo boost preasure, engine temp, battery level, etc., etc.. It will also correct any DCT codes that might come up.
I show no difference in trans temp in or out of tow mode. I just put it in gear and let the Duramax/Allison figure it out. If it needs another gear, it will go for it. I figure those folks at GM and Allison are a lot smarter than I am.
Also, I drop 2 mpg from 60 to 70 mph. Cruise control stays on 65 mph if traffic will allow.
And yes, the tow mode WAS put on the truck for a reason, it's for IF you need it. That is why there is an on/off button.