in my mate's case he got what he was quoted.
Same for me with a similar site when i sold my motorbike.
In my experience if you detail all the faults then they've got nowhere to go and nowhere to negotiate on. IMHO the issue is when someone says "no bodywork damage" and then turns up with a few scuffs etc. It's better to take the hit of a few hundred quid online and then give them nowhere to go. Although i think they are a franchise so your mileage may vary there.