I've only one MPP - a Microcord but I have used their website. It's been stuck in a time warp for quite a few years now but having said that it's not easy to maintain and improve a site which has a limited scope. Graflex.org is an example of a slightly larger and a bit more active website with it's own forum, useful for those purely Graflex questions etc.
I can't see any benefits to the Users club other than the Newsletter, however a more open MPP User group with a forum might well attract far more people. The Graflex Historic Quarterly magazines are online & free but even they struggle now for content as the old collectors begin to drop by the wayside.
There is a need for new blood to revive the website and it's content and more importantly be a better resource for MPP users.