A membership website can be difficult to manage, as it would require consistent content to be added. A lot of models are focusing time on cam, where they can build their viewer base, where they can interact live with their viewer base, and where they make the bulk of their payout.
With a membership website, it can be a good idea, if you plan on making a large amount of content, over a good period of time, and need an effective way to offer the content. If you are planning on making limited content, over lengthy periods of time, a membership website would be almost useless.
There are a few websites out currently that provide a mass model membership model, where each model has their own website, but it is handled under the same system, or you can always develop your own.