Hobie Fleet 32 has been using on-line registration for some time now and it has been very successful. We do not require fees to be paid up front - we just want an idea as to who is thinking of showing up. It helps more than one might think.
Our fleet even offers to host and set up on-line registrations for the fleets in Division 9 and neighboring fleets. We did it for The Kerr Lake regatta, Duck Cup, for the Carolina Beach regatta (When it last ran ) etc.
We charged a late fee for on-site registration/day of the event entry fee's for our Labor Day event and surprisingly I think only one or two people did not pre register.
I would hesitate to do away with on-site registration as some people really don't know if they can make it or not. Work, family problems etc can really dictate that outcome.

Tracie