Last weekend I did some power/thrust testing of the scorpion 4035-250 motors and hit a couple snags. I'm not getting near the thrust numbers listed, and the Graupner E-Props are experiencing some kind of blade resonance. Scorpion has some very elaborate charts for their smaller motors, and I've found them to be extremely accurate. The chart listed on site with the motor above appears to be fiction.
Prop options are limited in counter rotating pairs. APC has a decent selection of electric "pusher" props, but I haven't found them to be very efficient.
I'll do a little more testing, but I'm considering going with four 4020-630. I have a lot of experience with this little motor and an interest in exploring the push/pull configuration with brushless motors. You lose some efficiency but it is a setup that is used in the heavy lift drones to achieve redundancy with minimal structure.
Time to do some testing to see what kind of thrust/noise this setup will generate!