I have a Canon Powreshot sx1 is. I want to get an external shoe-mount flash for the camera. I have two options...

1. Canon Speedlite 430EX II E-TTL (Guide no. 141ft.)
2. Sigma EF-530 DG Super EO-ETTLII (Guide no. 174ft.)

Canon has assured me that the first flash will work with the camera. I cannot find any information anywhere on whether the Sigma flash will work will this particular model camera. All the reviews I have read about the Sigma flash have been very positive, but I don't want to buy a flash that I don't know will work with the camera. Does anyone have any knowledge about the compatibility? Thanks very much.

Joseph E.