Thank you DebitMe for confirming what it is that it is expected to be signed.
Thank god you posted up. Everyone chose to ignore me mentioning WoT Bitcoin address!!
[BTW] Once a deal has been struck my friend selling the account can ask theymos to confirm the IP of the account being sold has been the same since day #1. Hows that for evidence

I am guessing Theymos would help if the user whos account it is requests it the check, right ??Theymos should be able to spare 2 minutes hopefully.
That surely beats any signing... Signing relies on a password and keyfiles. Having the EXACT IP address since day #1 relies on a shitload more.
Now hopefully we can put the signing issue to rest.. But if it helps they will do the IP check and the signing.