Well, I don't actually know, but IMHO the upgrade/new user ratio must be at worst 50:50, especially given the old users tend to get their upgrades right after release (or even before!), something very important for a company who needs some fresh cash ASAP.

My point is, yes, they sure need to cater for the old clients. At least as much as for the rare new ones (those who were not attracted by DAZ Studio, its features and the free version...).