SD. Final delivery is SD, so there is no sense in destroying the SD material by uprezzing it first and downrezzing it later on export. Simply use motion/scale to downrez the 'HD' material to SD. BTW, 1440 x 720 (9 Mbs) is a weird format, where does it come from?
Thank you for your quick reply. What is "motion/scale to downsize"? When I import clips to PR Pro, I shoudl simply select 720x480 sequence?
Sorry, i meant HD 1440x1080. Tomorrow I'm shooting day 2 of a dance recital. I'll make sure both cameras are set the same this time.
You can set your preferences to Default scale to frame size, that will make all your HDV material to fit to the SD sequence automatically, or alternatively use the default Effect Controls/Motion/Scale effect to downrez HDV material to fit the SD frame. The latter is more work, needs to be copied to each and every HDV clip, but gives you the opportunity to correct for ill-framed clips with the Position control..