Simple question:

If the Canon sensor, in addition to deliver the details I get with my SD1, is capable of providing less noise at higher ISO the answer is yes. The variety of existing accessories for Canon and Nikon is just one reason. I recently was searching for remote triggers with TTL and could not find any for my SD1, they were mostly for Canon and Nikon. I decided to buy Pocket Wizard for Canon and manually set the flashes to be used with my Sigma.

BTW. I own a Canon EOS 7D and a Sigma SD1m. I use the 7D for birding, some Spectroscopy and the SD1m for everything else.