I just got a Dwyer VFC-141 off e-bay. Mine is 2% through the scale. It also have conections at the bottom and top instead of the side which takes 2 restrictive 90's out of the loop. And it is 1" connections so I am not expecting a killer flow loss. I plan on using my Hydor500GPH pump (same as the one pH uses) so power shouldn't be to much a problem anyway. That thing has some serious pressure.
http://www.dwyer-inst.com/htdocs/FLO...-VFCIISpec.CFM
Anyway as with you i am going to work with what I got untill I can get around to ordering the parts to my "good" test bench.

Looks like finding a distributor for the SwissFlow SF800 meter might be a problem...