Hi Old Fella,
L1011 APU's were not particularly efficient at best.
We operated the original -1s and 50s, and the APU was so efficient that we ran an air conditioning pack at the same time as we started the engine (apparently to avoid a pressure surge when the starter motor cut off). I can't remember any significant differences in the starting times between any of the engines.
When using a ground pneumatic starting truck, we'd start the engine closest to the truck (due leaky pressure loss).
Ah - those were the days - I'm envious of 411A.