To me 3% seems extremely low. The composers contribution to an event where the performer probably get 50-85% is worth more then 3%. 10% doesn't seem to high.

I would only support it if PRS removed their extortionate fees for small events in pubs, their rate for a typical singaround I've been to is 50-100% of the revenue - and they seem surprised their fee often gets avoided, quite illegally of course.