The 580 EXII has a pc sync socket, it's hidden underneath the weather sealing on the left side of the flash. It also has a metal foot with a very good mounting system, which I'm happy they went with - the rotating circle they used to use for their tightening of flashes was too flimsy, and could break fairly easily. I don't want an Omni-bounce with my Canon flashes, as I'm happy with a bounce card attached with velcro for my purposes. If I want an omni-bounce, I'll either make one myself, or purchase one for $20.00.
The 580EX II is no slouch, and neither is the 430. I've tried using Nikon flashes, and I'll be blunt - their wireless system with Nikon Commander just requires too much babying to really get it to work. The flash itself is good, but I don't care for too much on the bells and whistles, I want a flash I can control quickly and readily, and add modifications as I see fit.