The last issue of "Shops and Tools" from Fine Woodworking has a nice
overview where they evaluated volume and linear flow rates from a
variety of collectors and prepared some comparative figures showing
what you can expect from various-sized single- and two-stage collectors
from 1-1/2 to 3+ hp. I assume you may be able to find the article
online at www.taunton.com, perhaps. If not, it would definitely be
worth a trip to the library and if you're serious, probably the few
bucks at the newstand.

Is that a special issue or something? I am looking to buy a cyclone and
they are sufficiently expensive to justify a little research. Thanks.