Joseph,
From you post it sounds like you folks have your act together. After some of my selling adventures it is my opinion that your fees are very reasonable. I am not at all surprised that a pro can do the job cheaper than an amateur.
I am glad that you have joined us with your knowledge. I think that a lot of us are a bit leery of brokers because of our lack of experience in dealing with them. Perhaps you can make us all more comfortable with the advantages and of course disadvantages of using a broker to sell our planes.
Maybe a short tutorial here in the “Buyer & Sellers” forum would be in order?