There is no reason to use sports mode. I used the standard Steptronic mode, except when the X5 hunted between two gears on a grade. In those cases, I shifted it manually so it would hold the gear. I also used the manual mode when descending, so as to provide engine braking on a long descent.

A point to keep in mind is that it isn't just about what gear you are in, it is also about whether the torque converter is in lock-up or not. When it is locked up, there is far less heat generated. You want to select gears such that you keep it locked up (it will unlock at a certain speed as you lose speed on a hill, and it feels like a shift).

I continue to think that the X5 is an excellent tow vehicle, but a large part of that opinion is related to the stability of the combination of the truck and trailer. It simply isn't going to drive the same as without the trailer, due to the added weight. It may be that those who have spent a lot of time towing know that instinctively, I am not sure. Just because it tows very well (IMO) does not mean that it accelerates and stops the same as when the trailer isn't there.

__________________
2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue