These kind of large transactions you can't do them on a P2P exchange and you cannot do them in the street !

These are a serious thing and must be done in total privacy and also to not affect the market price.
Usually are done with brokers or large miners.

Ok then I'm this case I guess P2P option will pose a big threat or at least uncertainty.

ch0k1

OTC is kind of P2P, but are you able to handle a large transaction?
This is not about 20 bucks, or 1BTC, is about LARGE amount.