I'm tinkering with this thought too, Mick,
I recently lost a ball on St A's and without realizing it was my last, was forced back to the starter balls. This was right after a very frustrating round where I couldn't dial in my new master tier drvr or my new wedges, and was having a hard time gauging distances on those wedges. I'm not jumping ship on the upgraded balls just yet, but I can tell you that I saw an immediate difference in my accuracy with that driver and all those wedges, and it went up considerably.
The drawback is easy. Less spin to stop the ball on those downhill / downwind approach shots, and reduced length off of the tee. The tee length especially hurts on those long but eagle-feasible (new WGT term?) holes, and for that reason alone I will stay with the upgraded balls and give myself a chance at reaching the par 5 in two regularly.