To go back on topic, I definatley think there should be some form of enforced promotion/relegation going on - I think the only problems that relegation would cause is sponsors being unhappy about their chosen team being percieved as slightly pants
Obviously there would have to be something done to cover the "but we only played one leg, you can't relegate us" syndrome.
How about, from the six event, you need to play 4 to be ranked in the "league tables". However, as some teams may only be able to make the four events, the best four results are used from the season, those teams that play all six legs effectively "drop" their worst positions. This would get people trying to play more events too, to cover their backsides for when they have a bad tourney.
In case of a draw, the total points scored in the four events can be used - my thinking on this:
If it took 600 points at event 1 to come 4th, and 800 at event 2, event two must have had play of a higher quality, so the team with more points gets the promotion.
But anyways, who needs a proper league structure - I mean, I can't think of a single "recognised sport" which uses leagues