Up until now, I have been perfectly happy to only use stateless session beans in my application.
And, I have been able to do a lot of optimization to speed up the user's experience.
But, if I can avoid reloading large data structures every time the user is making a change to them - then that should be an additional (and possibly very large) speed boost.
Plus, I would be able to make changes to the data structure separate from the back end database without trying to cache it on the browser - which would be a nightmare!
So, I am finally going to try to use a stateful bean. If it works (if I manage to make it work) then I'll get to rewrite a -lot- of code to take advantage of stateful beans.
If it doesn't work, then at least I already have everything working with stateless.