Only time I kick people out is when I see them being inactive for a long time. This is after all a game you want to do some progress, even if ever so slightly. As there are a lot of allies iny my list who have good Power and Speed, I dont really care for the rarity of their characters that much.
BTW I wanted to say this some time ago but never got around to it, but that Shinobu avatar is damn cute![]()