You have quite the strobist setup there... stick with canon i have only the sigma and it SUCKS.. lol recycling time is so bad i left , got a sandwich, and came back before taking another shot..... besides that it is very LOUD the zooming is louder than any camera shutter and it sounds like its broken when it realy is not... i made apoor decision buying it but i do not have the money so its all i got for now .. save yourself the hastle and go with canon. I would get the 580 ex II ,,, my friend has it and i have used it many times, it is amazing compared to mine. hope this helps and good luck