Mike, I'll have to say, that was a nice, informative email!!

I happen to run the axi and I will agree, it's too quiet. I could use the gearbox whine sometimes. Maybe I should mount an aluminum can to the prop to get some noise!! haha
As for lithium and regulators. Well, after losing two planes, well three, (but who's counting) this year I have settled now for a 3 cell pack and the jaccio switch regulator combo. If a cell goes bad I still have 2 cells, which is enough to fly and land.
The jaccio fails open so you still have control if it fails. I'm sure you know this though.
I have a friend that runs two 2 cell lithiums and two switches. This works for him but I feel comfortable with my setup. I don't see any need for you to change as you are within weight and are comfortable.

Sure is a nice plane!!!

Chris