I've been doing big edf's for a couple years now and smaller ones for 5 years...

I'd go for the lighter setup...it's going to fly better and have longer flight times and cost less

Tam also sells a low amp version of his fan which could be a smart setup... he use's smaller lighter motors and CC 85 hv's to save weight
with his new 7 stator design and soft mounts.. at these low amp levels it will sound pretty nice...it's at the high watts it really screams

This sounds crazy but talk to Tam I bet it would work very well...
Drop down to his 6s setup it's only $699. plug and play with fan, motor and ESC, it only weights 1.2 pounds (these two fans would weight less than one dyn-e-max and the dyn-e-max still needs a ESC and CC 110 are over 5oz)
So just in the fans you save 2 pounds over your tubax or dyn-e-max setup ..that puts it at 18 pounds...
now you only run 6s per fan..a total of 12s 5000 mah.. so by droping from 10s per fan to 6s per side you save another 2 pounds..
so you hit 16 pounds.... if the CG works out... but I bet it would
on a good 6s 35c 5000 mah pack Tams fan will make 2000 watts (so a total of 4000 watts)

Put's you right a 250 watts per pound ... spend only $1400 bucks in fans and only have to run 12s....

I think that could be a killer setup as much as I love Stu's fan .. I think I'd try this setup
Ron