My 2 cents worth, no. Unless you're in a room with completely parallel walls, the chances of getting any cancelation or comb filtering in a pub/club full of chairs, tables, punters, bikes on walls etc, I'd have thought were 0. Not to say that it will probably sound different in different areas, but I wouldn't have thought that was due reflected cancellation.
@Phil Starr interesting video, but unless I've missed something, you're man seems to miss that an audience will stand in the middle of the room, not in "middle middle", so on his model they get no mid/top at all.