Where to leave Itrader? just this site? others?

hey all, sorry if this is covered somewhere else, but I have a quick question.

lets say the following situation happens:

BillyBob lists some samplers for sale on here, as well as CigarLive and ClubStogie (i say those since they no longer exist).

I want one of the samplers and pm him about it here, and end up buying one or two.

Obviously I should leave him feedback here, but should I also leave feedback on CL and CS? where he also listed them?

What if he didnt list the sale on other sites, but I know he is still a member, should I leave feedback there as well anyway, since trade reputation can be very important at times? Since he completed a successful trade on another site, it still makes him as equally reputable on another site does it not? at least to me?

I was just curious about this and thought I would ask. Thanks for the input in advance.