My Integral was purchased one year ago and flown this past season. The manual says the CG should be at 205, but Jason subsequently suggests 190, and I currently fly mine at 150! This means that the CG is exactly on the nylon wing retaining bolt. I have the 170DZ, Hyde AR, and short pipe. I use two TP910 LiPos mounted just behind the landing gear and the Rx is up in the turtledeck behind the canopy along with two voltage regulators. I use the stock CF gear that came with the kit. I had originally put almost 4 ozs of lead in the tail but have removed all of it since then. The only mod I did to the plane was to put Gator stab adjusters in the tail because I thought the stock incidences were wrong, but in the end I am back to very close to stock. However, the plane still pulls to canopy on up and down lines, and moving the CG forward has reduced this quite a bit.
Structurally, I agree that the CF ending 4 inches ahead of the spar will make it fragile, but I think that to offset the fragility of the kev/balsa fuse to bring it to the same resilience as fibreglass would need CF all the way back to rear fuse. I have had both some harder landings and some "hangar abuse", and the plane doesn't seem to suffer too much.
I bought this plane as a replacement for the loss of a previous plane, and I was looking for the lowest cost ARF that had a reasonable track record. That is exactly what I got, and I can see that it has good performance. However, it is by far the most difficult plane to trim that I have ever owned.
You buy the meat, you buy the bones, as famous man once said...

John

(Pic of my plane at NSRCA D5 page)