Metric BJ4?

[U.S.CAT3K]

It seems like the SAE screws strip the plastic parts on the car much too easily and was wondering how much modification, if any, was necessary to outfit the BJ4 with metric screws. Only looking to do this to the gearboxes and I do realize that the holes will have to be enlarged slightly, though I'm hoping that I won't have to change the countersinks in the carbon and aluminum parts to get the screws to sit flush.

Will 3mm screws hold well enough to consider this a worthwhile mod?