Love them! They will cause more lawn damage than hand dragging if you're not careful, but they are great for saving the backs of the crew. Less pain=happier employees=faster jobs=more $$!
More control for pulling trees than a truck - works like a charm.
I can remember feeding 80' trees through a 250XP using the winch. Soooo much easier than limbing, bucking, and carrying the material to the chipper. Also, you can make one heck of a big pile, choke it, and drag it, then toss it in the chipper. If you're good enough, you can set all the butt ends on the feed table with the winch, the all you have to do is stuff them in...And if you have too much material in the feed wheels and it won't feed, wrap the cable around the pile and pull it right on in there!
Problems...The cable would get all sorts of tangles if someone wound it in without any tension on the line. That would kill about an hour of productivity right there...And those cable burrs hurt like crazy if you let the cable run through your hand.
Although I've only done it once, you can also use the winch around a sturdy object to pull the chipper backwards (not attached to the truck, of course).