One major question is privacy, how sure can anyone be that you don't sell their information OR better yet, that your site is secure enough not to get hacked. Remember, you're in a shared enviroment, you can have the host themself, other clients, or even anonymous people steal the info from your site. See, nothing is 100% secure no matter how hard you try someone WILL steal things if they want it.
All in all, I wouldn't register with the site because the concept is that the buyer of equipment would need to check the database. Chance are if something is stolen it is being sold for way less than value (pawn show or out of some guys car) and you already get the feeling that something is not legit about it. The people who buy stolen goods simply don't care who it was stolen from, they care that it is theirs now.