Screw the whales......

....save race day registration (RDR).
The ability to register on race day is ultimately a service that promoters have provided since the crust of the earth cooled (thank you). For big races I will acknowledge the need to have preregistration, but for local XC events?
Promoting a race is a big financial risk that is incurred on the part of the promoter, and the promoter should have every right to hedge his or her self from this risk by paying out according to class size, combining classes, etc.
However, preregistration does not help manage your risk since 80% of your costs are fixed, and will be incurred whether or not people show up. It does help streamline the registration process and make things flow a little more smoothly on race day, but most promoters just give a discount to encourage preregistration/discourage race day registration.

I, for one, am not going to be able to go to AR this weekend due to work conflicts (and am out $65), and thought I might be able to squeeze in a XC race on saturday, but required preregistration means that if something else at work changes I am out of a entry fee.
The ability to register on race day offers flexibility.
I place a lot of value on flexibility. I have no problem paying a extra $5 for RDR for a XC race or even $10 for RDR at a endurance event.
By all means encourage folk to utilize preregistration, but don't limit your clientele by requiring it.
Thats all I got.