When I was a full-time IT industry analyst, one of the things that regularly annoyed me was overly large tables at dinner. A lot of factors were in play including the fact that many analysts felt very strongly about being at a table with the "important people" (tm) in the room. But if you were at even a round table seating 8+ people, it meant in practice you only talked with a few people who were reasonably adjacent.

I would say a 4-6 person table is about the largest where everyone can be talking with all the other people.