I have a 5-stone with 10 pointers - not an eternity, but maybe I can help? I haven't had any trouble with stones falling out or anything, but I don't wear it everyday either.
The only person that I can think of who owns a shared prong eternity of less than ten points per stone is vespergirl, but hers is not a Uternity. It's a beautiful WF shared prong band of eight point stones. You can find it easily if you search her name.