Bill: The heat transfer is much higher with liquid like oil than air in an oven, but that's not really important in tempering. You're just sticking it in an oven for 1-3 hours. The rate at which it first reached temperature isn't that important.
Delbert: You've been listening to Kevin Cashen too much, bainite is fun stuff, if a bit over-hyped. Certainly in kitchen knives where hardness is king there isn't much reason to heat treat for bainite. However, as you say, martensite is great.