True, that. The better manufacturers like Can, Vortex, Soler & Palau (probably some others) publish charts and/or graphs of fan performance at various static pressures. That's not true of the cheapies.
Some of it, I think, comes down to the specifics of a particular installation & personal preference. Centrifugal fans, like the Vortex, will generally do better against high static pressure in elaborate ducting, long runs & so forth. The mixed flow fans are more compact, and the S&P mixvents allow for easy changeout of the working parts- no duct removal required. The new Vortex S-line is similar in that respect, and also integrates a backdraft preventer. It probably blocks light when the fan is off, I suspect.
In my situation, a S&P td-125 has worked well in combination with a cheapie craigslist 4" centrifugal that I got for $20 bucks when I needed it. We had a ridiculous streak of very hot & humid weather last summer. The S&P vents the reflector, only when the 1000w is on, and the 4" runs all the time to vent the enclosure. Both have Phat filters. I'll upgrade to probably another S&P instead of the cheapie when I rework the whole thing sometime next spring or summer. If I get the ducting right, I may be able to eliminate the filter on the reflector fan.
