Most Poser users cannot use magnets, create material or create dynamic simulation. I think that most of DS users are similar. For them only difference in Poser and DS is interface.

Few users find tools in both application which they need. For example somebody need clothing room, somebody need weight mapping. You cannot convice them that one application is better and second is worse. Just like cars. You can say that B Veyron is the best car, but if you must transport few tonnes of coal, each Scania is better.

ATM you do not choose software, but you choose features.