Well, I have had both mirrors (on 2 differnt trucks). The power mirrors are great for fingertip adjustability especially when u need to change the mirror for backing in somewhere. They usually also have a built in defrost, so depending on where u live, it is a pretty sweet feature here in the North.
Now the tow mirrors, I have gone through 2 sets so far. The 1st set's mirrors would not stay put. They just flopped around where ever they liked. I had to tape them put so I could use them. I had them replaced under warranty recently, so I hope these new ones last longer then the 2 weeks for the 1st set. They definetly do a superb job when towing & tuck away discreatly when in normal everyday driving.
I would just ask yourself if you really need the xtra length & larger view when towing. If not, then the convience of power & defrost wins out in my opion.
Cole