Dingbatt: I guess the only other thing to consider is that, because the agent works for the vendor (regardless of how much they appear to be your friend), they may have been instructed to not present bids under a certain value.
The best outcome I have seen (admittedly not in a frenzied market) was when friends employed their own agent to negotiate on their behalf. His payment was based on how much he could save them. In the end they reckon he saved them $80-100k for an outlay of about $5k. Plus much less stress.
Agents have to work in the best interest of the vendor, but they still have to be fair to the buyer. Although it is somewhat ironic, because it is the buyer who ends up paying for he agent, as the money usually comes out of the deposit the buyer pays.If I was selling, I would definitely use an agent to do the negotiation etc, they do have their place, but would do it on a negotiated fee.