As a chess-playing collegiate rower who likes engage in random debates with people, I think I've done all of the above :) Variety is definitely important to keep things interesting - I think getting stuck in one "niche" circle is fairly alienating - even if that niche group gets shit done. You start filtering people based on some common preconceptions. Being part of several different groups with differing viewpoints, on the other hand, should make you value individuality more and be a more rounded/easier person to be around.

Just my $0.02