The G11 will run better if you pump in 14V and over rather than 12V but I agree some other components such as automated focusers might be less tolerant, although I assume the manufacturers would take precautions and still be able to operate within a reasonable range.
Talking about tolerant circuitry I recently had a regulator fail on my car alternator. Weird electrical behaviour inside the car. Warning flashing erratically, radio on and off, wind screen wipers in turbo mode and a foul smell (hydrogen fumes mixed with sulfur?) The voltage at the battery connections (engine running) was 18.5V
. Got a new alternator, reset the computer and everything seems to be back to normal now. So there must be some tolerance in the circuitry.