Due to the size of properties and volume of leaves blower with tarps is really not too efficient for us. A bagger on a mower is not really great either because it has to be dumped too often.
It seems like all of the decent sized properties that I will be performing leaf cleanups on this year have some obstacle that prevents a big mower with a bagger (or something big like that) from being used. My biggest job I just got is in a heavily wooded property. There is very thin grass, with lots of small flat rocks, and acorns everywhere. I would surely break a window doing it with a mower (although I might break a leg doing in with my blower because it is very uneven and rocky terrain).
Other yards it might just be a certain part of the yard that I can blow directly to the street. So for me the backpack will work best. I just want to get out and use it. I am talking with some of my customers now about what they want me to do with the leaves. Their options are A) they take care of the leaves and I continue mulching the grass like I do April-September. B) I just mulch up the leaves as best I can and whatever it looks like it looks like, or C) I take care of bagging/blowing the leaves to the curb, for a price added on to the regular mowing price. All have chose "C" so far. Which is fine with me, as I like leaves.