Sigma 500/530 vs Canon 580

[Ockie]

I've searched around here and on a couple other forums, but I can't find a thread with the same question... so here it is:

I currently have a Canon 400D, and I might get a job for a couple of days as photographer at a local film festival, and I want to invest in a decent flash...

except for perhaps this event, photography is just a hobby for me...

my question is:

what flash would you recommend me, the Sigma 530DG Super (or the 500) or the Canon 580 ex, keeping in mind I'm not a pro?

The Canon is quite more expensive than the Sigma... and I just don't know if its worth the difference for me... I hope to upgrade in a couple of weeks / months to a 40D, and I might be 3rd shooter on a couple of weddings this summer...

I hope my question is more less clear ;)
PS: The flash I saw on e-Bay has the following name "SIGMA EF-500 DG SUPER EO-ETTL" - for canon, checked that :)

[Curtis N]

Either the Sigma Super or the Canon 430EX Speedlite would serve you well.

[martinsmith]

I have a 580 exii and I'm no pro. If you can afford it, buy it. If not go with a sigma.

[Ockie]

I have a 580 exii and I'm no pro. If you can afford it, buy it. If not go with a sigma.
right now I can afford it, but the more I spend on the flash the longer it will take to my next upgrade :)

I mainly like to shoot with available light, but a decent flash can never be a bad thing to have...

[martinsmith]

Go with the cheaper options then.