Can tell you from my own experience trying to start two different casual end game shells back when I played that they work great at first but give it a few months and it flips on you.
People get pissed that most the shell only shows when they need items (like lots of normal end game shells) so the lesser needed items or for people who just like to collect EX items for their jobs, they get left out and usually end up leaving.
It's a great idea in theory but damn hard to put into policy and have fun. It was a headache for me to try to run both both shells ... whiners will drive you mad as a shell leader most the time!!
You best bet is to try to find a end game shell that only does a few events a week. One during the week and maybe one or two on the weekends is ideal for those with a heavy work/school schedule. Most importantly, you'll need to have a great group of friends willing to help everyone out even when nothing is in it for them besides your thanks.