no, keep SP gain simple.
our first SP gain system which requires you to do action and are completely random was a complete fail design, it was hated by everyone and for god's sake i never want to see that again.
just kick if u are having a member that leech your party, but in my case i have alot of friends that have children and sometimes they have to go afk to take care of them.. i'd hate seeing them to fell behind in terms of SP because u know they have another lifes they have to take care of.