About the runtime or voltage preference, running substandard packs on the brushless makes a huge difference, whereas running the same packs on a brushed mod I hardly notice any difference at all. The motor seems to behave a bit more like a fast stock motor, so any packs I buy I'll be looking for higher voltage as runtime is never really an issue.

The big numbers could also be at a 20A discharge rate (which you probably know anyway) but this'll yield 1.18x - 1.19x type numbers, whereas mid 1.17x is more like it.