I wish DGSlayer or some dev could answer this...
Is it possible now that the market is opensource that someone could modify & compile their own client but with code that would be circumventing things like the escrow system or somehow cheating the escrow system?
Maybe opensource is actually a vulnerability in this case? I still would not use a closed source market though
I don't know, I hope its not some kind of weakness.
The market uses multisig as part of it's escrow feature... if somebody modified the code and the new version didn't have multisig
then it wouldn't get accepted when transacting with a non modded/unsafe version.