Roots or screw-non racing ap

I was about to buy a cement blower for a truck when I found a new model that is a screw. All the older models are roots. The screw comes with a gear drive so I imagine my engine/pto rpm will be the same with either one. My question is what are the advantages and downfalls of each concerning building heat, service life, service cost, noise, air flow, pressure?

See as how this is WAY off racing topic, if you choose not to clutter the board, you can email me direct at farmboymotorsports@yahoo.com

By the way, I ask here because you people know more about blowers than the industrial salesmen.

Thanks much