Unless you have already posted an address, then a signed message is going to be of very little use to a potential buyer as any address posted after the hack should be taken with a grain of salt. It would be possible that someone could hack an account after the forum hack, post an address, post normally for a few months and then try to use a signed message from the above address to prove ownership.
I think it is pretty rare that someone would not ever post any address after being here for at least 9 months, especially considering that you must post one if you wish to ever enroll in a signature deal
Never been involved in any signature campaigns, taken out loans or given loans... I only ever posted in altcoin section, projects, technical support and sometimes here (digital goods), My posts are generally just helping people or Bitcoin discussion. I especially wouldn't give an address out on here unless I had to due to dust advertising.