bgill,
"great minds . . " Looks like your decison has to be when to spend the extra time (you need the extra disk space no matter what).
Taking extra time after the import minimizes the total time lost (since you do this rarely) BUT it's when the **** hits the fan that you need to act fast, so there might be an argument to make the export job "slow" to enable you to do an import at top speed.
"The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman