ultimatly it comes down to what it will be going out at. I am assuming it will be HDV in the end to keep it HD. So from there when you drop your minidv footy into the HDV AIC timline (apple intermediate codec), the mini or sd stuff will render to the HDV codec. Then I believe you'll have to do some scaling from there.
*note: I haven't actually done this but this is a guess from all the information I have read from other forums. If I am totally wrong, sorry in advance.