We have moved our CG quite a bit back over time with no problems I'm guessing behind the wing tube (I have the ultra lightning) we will check it once our new balancer shows up also.
I have reduced the flap 15-20% and added as much crow as travel will allow (around 1inch up) which helps the plane settle constantly thru ground effect. It very deceiving as it will fly much slower than most are willing to fly it! and has a lighter wing loading than the ultra flash and carries energy due to weight much better than the flash which makes it appear harder to slow down. Just takes good energy management and practice, its a great flying plane.