Thanks for the replies ..... I agree that near the top then the differences in each event matter, almost whatever distances, but as you move down I think the bike is where the biggest time gains/losses can be made - for example a poorer swim might cost me 2 minutes but a poorer bike ride would be 10-15 minutes.
Didn't mean to start argument and admit I am biased as cycling is the lesser of my three - eg. apx. 40th runner, 60th swimmer, 230th biker on Sunday (out of 700).
Anyway original question stands if anyone is aware of such events?