Certainly, the 430 and 580 are more powerful, so it seems to me that the main question is just that - how much power is enough, and at what price ?
I have a 380ex, and it has served me fine, but I bought a 430 just recently (I needed a flash in a hurry, and my 380 was in Spain..) and have not yet noticed any real advantage, though there have been times when the 380 being bounced of a high ceiling has run out of power...
Hope others can give you more useful advice !