The 580EX II is a buy it now and use it. The assumption is that newer units are always better but not in every respect, it may not interface with older ( or your camera) as well as it's contemporary model, in other words there may be features the newer model doesn't have that you might have used in the older model. Other possibilities are the interface may change and not be as much to your liking as the older model. Another reason to buy now is that the older or newer model could be relegated to slave flash status, and as you add lights to your arsenal you can achieve more balanced or creative lighting techniques that single flash doesn't allow. It's fun to take old strobes and make them shine again in multiflash setups for which they weren't intended, some photographers use Vivitar 280 series flashes from the 1970's and obtain spectacular results. Canon should be applauded for making the 580EX II bulletproof, the foot and the seals including the door are very well made. One last suggestion: buy it, use it, sell it when the newer model arrives.