Very interesting...
Thankfully the plane was in a dive when I got the spike in RPM and dip in current/power. (Funny the first thing I did was check the prop adapter to see if it was slipping and it wasn't).
Hopefully this afternoon I can get a flight in and be able to get a bit more data. I am going to set up the camera on a tripod near the runway and see if I can get some data for doppler readings. Right now while I have data from the ESC I have no idea of what the flight speeds are.
I'm still pretty sure that for any real speed I am going to have to try this setup with either a 4 or 5 cell battery, the motor is supposed to be able to take a 5 cell in burst operation. The one down side of the higher cell count is having to go with a new charger as well. My current charger for Li-pol batteries is around 7 years old and can't handle the new high current high cell packs.
Still when it comes to prop selection I am guessing at what I am doing, right now I'd like to try a prop that is about the same diameter with more pitch, something like a 5X7 or 5X8 would be nice.

Edit to add:
Has anybody seen this plane?
http://www.boeing.com/Features/2011/..._05_04_11.html
They stole my fuselage idea! lol