The wheels suck. They just make it so the unit blows everything foward. My guys hate that. They like the straight shaft unit quite a bit. It will allow you to angle the head so it will sweep away from curbs and such.
My guys also like the Stihl with the rubber paddles instead of the brush. The brushes seem to bend and cause the tool to bite down and bog the unit down. The paddles don't do that. They will also loosen and sweep up caked mud and deep sand.
One of my units is the Stihl Combi system. Its a power unit with interchangeable shafts. Its got the rubber head on it. I also have a Yard boss, Its got the brush head that the guys don't like.
We also take the big ass gaurd off. Its heavy and ackward, and the guys realy hate it. The units don't throw stuff to much, they keep it close to the ground making the gaurds kinda usless anyway.
With the paddle head you can sweep gravel out of grass after the snow melts. my father in-law bought one for this purpose and was not dissappointed.
I have said it a thousand times. This unit is my best tool purchase ever. The first time you use one you will understand why.