Interestingly, now that you bring this up, I'm not at all certain that I'd be able to communicate especially effectively with a copy of myself. Probably better than with a randomly selected person, but perhaps not as well as I might hope.

What makes you reach that conclusion?

I think communication would start out good and become amazing over time. I don't communicate with myself completely in English, there's a lot of thoughts that go through unencoded. Having a copy of myself to talk to would force us to encode those raw thoughts as best as possible. This isn't necessarily easy but I think the really difficulty part would already be behind us, namely having the same core thoughts.