Don't see the need for a water proof ground sheet. A decent tent floor should be water proof enough. A water proof ground sheet is only going to pool water from tent edge run off or condensation. Better to use open mesh as required in some places.
Fair call, both types of groundsheet have their purpose though. A waterproof one will keep the area under the tent cleaner for pack-up, and drier provided you set it up to minimise the pooling you mention. I, like you, do like a mesh groundsheet though, offers a good balance of everything. ~ Ben
