I can only speak for how I use it only F53 chassis. When in Tow/Haul mode the transmission will stay in each gear longer as you accelerate from a stop. It will down shift more quickly when going up inclines. It will also down shift appropriately when you apply the brakes. This is extremely helpful when descending steep, moderately steep grades, or while I towns or traffic.
When I am on relatively flat interstates or major highways I usually have it off as don't like how quickly it downshifts sometimes. If you have it off and the transmission is constantly shifting backhand forth, called gear hunting, then put it in Tow/Haul mode, that will stop it.
You really can't hurt it so play within to see what's comfortable.
Paul, Kathy, and Tux the Mini Schnauzer
2014 Tiffin Phaeton 42 LH, 2013 Honda CRV
"When the time comes to look back, make sure you'll like what you see"