I agree..Still no matter what you do, there would be some dust and moisture that gets in from the top (even with new window scrapers) The key is to not forget cleaning the door insides and lubrication, say, every year. It is not a recommended-by-VW service interval but I have seen a lot of otherwise good doors rust at the bottom just because the owner never bothered to check the insides of the door or remove the accumulated dirt, clear the clogged drain holes.
Prevention is better than cure.