One of the problems with the pistol grip set up is the weight and shape either above, below or in front of the handle and I can best describe this aspeed by comparison with the old Jim Walker UReely which I am sure you know was somewhat ackward with its mass considerably forward.
What I fround works best in my years with the Bill Young pistol grip is to simply keep the throttle nailed as if there was no throttle during all maneuvering and pattern stuff. Only reducing power for slow speed stuff, touch and goes etc. It is during this slow stuff that precision throttle positioning becomes most difficult with a pistol grip.
Now with the 2.4 tranny on my neck this difficult throttle positioning is very easy and far more preferable. Also I do not keep my free hand continuously on the throttle, not necessary and not needed. So yes the chair flying is possible and practical while stil multi tasking with the free hand. I have had a considerable number of flights on a Kaos, Magician and a Jr Ringmaster over the last two years using 2.4.
For whatever reason my Magician by going inverted and up to a 45 degree angle to increase the rotation speed will by using my free hand to lock one wheel and raising my good foot will spin me until the tank is dry or my arm becomes exhausted.
John