We never had this kind of problem while changing heads on Samsung drives. Samsung tools are in regular use in HelpDisc for few years already and many successful head swaps were performed on Samsung hard drives - however this heavy stripped head screw problem never happened.
Even no one from our clients who bought our Samsung tools had complaints on such issue.
So I suppose that problem which have pclab is really uncommon - that head screw is so stripped that even big flat screwdriver can't loosen it and allow heads to be dismounted from the donor drive casing. If flat screwdriver directly can't loosen the screw, surely it couldn't be loosened over tool shaft. Obviously it is drive's, not tool's problem.
I said to pclab already - drive from which heads can't be extracted can't be considered a donor drive.
Pclab, have you solved problem in the meantime? You found donor drive from which heads can be extracted?