"Also, by charging a percentage what incentive is there to waste time on resubmitting a secondary claim 2 or 3 times when needed."
Michele, you hit it on the head. A person with a GOOD work ethic does things right the first time so they don't have to do it again. On percentage, that's just a waste of time! On hourly, it's a waste of effort.
This isn't piece work! Do a good job, or let someone else to a good job!