Jim,
I certainly, unfortunately, know what you're talking about. I'm the senior developer for a large company with 7 ecommerce websites. Whenever something goes wrong on a site someone will send me an email with the error, but won't be able to tell me how to repeat the problem (I don't blame them). Then I try to recreate and can't... You know the rest.
So here's my suggestion: You say half the bugs you can crack easily and the other half are hard. I think you should send half the bugs to prolific. You choose which half.