Hi!
I have had my GP GEE BEE R-2 now for 3 years , flying it approximately 15-20 times. Despite being used to flying fast airplanes this one takes some time getting used to. I have been flying pylon racing for more than 25 years and thought I could handle most airplanes but this one was a beast at landings.
There is no problems taxing and take off is very easy (I'm using a ´MVVS 15cc (.91) two stroke and 15x4W APC prop) and so is flying.
It rolls good and knife-edge forever.
The problem is landing it!!!
It seems to have a very narrow landing window between a perfect landing and disaster!
If you come in too fast the wheels grabs the grass ... the plane tumbles...this despite near golf green facility... if you come in too slow ...she suddenly just doesn't fly anymore and just drops...! Neither is any good.
The last time I flew it, this spring, I modified the ailerons to have more up throw than down and this made the landings easier. Cannot say I'm 100% familier with the GEE BEE yet, but the aileron modification seemed to help. Seems like one wing-half stalls when moving those big ailerons on landing and flying slow , and then she drops.

To have a light plane is vital! my GEE BEE R-2 weights exactly 5000g (5kg) and despite this low weight it's real hand full to land, at least it was until I put in some aileron differential.
So build it light and remove anything that isn't necessary and power it with the lightest possible engine.

What struck me the first time I saw the GP GEE BEE-R-2 was the wing sitting at 6 degrees positive and the stab 0 degrees. I think this is perhaps the factor that make the wing stall so early.
The Henry Haffke GEE-BEE R-1 I have been building the last 25 years... sic [8D]has the wing sitting more like 1 degrees positive. Have Laser 30cc V-twin on that plane.