Personally I swear by the Toro electric Ultra Blower/Vac/Shredder. It has a metal impeller, so it won't break like plastic impellers when shredding small twigs and such. It's variable speed, and claims to have a top speed of 235 MPH (255 CFM), but whatever, it is very powerful for both blowing and vacuuming and leaf shredding. It's relatively easy to switch between the blower and vacuum attachments. I end up with many fewer bags of leaves due to the shredding. Yes, it's a pain to have to drag an electric cord behind it, but I'd rather deal with that than the disadvantages of gas blowers. I would also recommend buying an extra vacuum bag; the zipper on the bag is the weak point and I've gone through 2-3 bags over the years -- you don't want to be in the middle of cleaning up your lawn when the zipper breaks and you can't continue. You can see it at
http://www.amazon.com/Toro-51599-Var.../dp/B000H1Y4EK