i got my opinions from reading programmers reviews of certain sites. they dont have the backend but they can do penetration testing from the outside, BMR, Sheep both have some serious problems apparently but reviewers say so far PBF is good. i guess time will tell if thats the case, but bmr and sheep have both shown weakness.
Where can I find that information? I'd be really interested in seeing something like that...
heres one about how shitty bmr is
http://www.reddit.com/r/SilkRoad/comments/1ophnb/black_market_reloaded_back_online_owner_backopy/
another about shittyness of sites
http://www.reddit.com/r/SilkRoad/comments/1olyb1/security_of_marketplace_websites/
blog on alt markets has some info
http://atlantisblog.org/191/
verdit some sites are really obviously shitty and some havent been proven to be shitty yet.