I'd have to go downstairs and weight this thing, but beyond that, I was surprised the 2 EDF50 fans with the older 4100kv bl Feigaos could ROG and fly this modified Cox airlifter quite well. The 5866 would simply be par for the course. The plane is around 40" span. Planes like Cox usually are nothing to write home about in terms of engineering, but I would actually reference this one. They were definitely onto something here, as the washout alone shows that they actually put effort into this design. In the case of this plane, a larger fan setup would have probably "ruined" the plane, as the weight gain from the much larger 20mm motors offsets so much of the performance gain. I'll have to dig up some relevant specs on the plane.
Specs are everything, as you know. My little brushed 12V EDF50 yellow DHL airliner was built to your wing loading spec David, and it worked beautifully.
I'm constantly more impressed with the little fans, as this 27" EDF40 ME262 was obviously not built to spec at 14.5oz AUW
and still flew beautifully. You really need to try the 5866kv 12mm motors if you haven't, as this plane needed every bit of the performance at that weight, but it was there.