I am curious. Why do you regret the move to C?
Ergonomics -- hated Canon ergonomics. Not only did the 1DmkII and 20D just not "feel right" in my hands, but I had to think more about what I was doing when changing camera settings ... unlike with Nikon, Fuji, and Pentax cameras where the controls are generally where I want them to be in terms of function. When covering weddings, if you have to stop and think and look at your camera to adjust a setting then you probably just missed a once-in-a-lifetime moment for the bride and groom. Ergonomics are absolutely a "personal" issue. I like Pentax ergonomics the best, but others love Canon.
Weight -- Canon DSLRs (particularly the 1DmkII) are heavy ... too heavy for my taste. Try lifting a 1DmkII, flash bracket, flash, flash diffuser, and external battery for the flash for 5-10 hours without a break. You quickly learn to pick the lightest gear that does the job.
Flash -- One of the reasons I moved from Nikon to Canon last year was the easy wireless TTL system. Unfortuantely, while Canon's E-TTL wireless system is easier to setup than Nikon's Creative Lighting System with the SB800s the Canon system doesn't do all that well in bright sunlight (like at an outdoor wedding). I got better results using cheap optical and radio slaves and manual flashes.
ISO -- Yes, Canon DSLRs produce clean images, but they do so by "smearing" certain textures. The detail would always be there in things like the beadwork on a wedding dress but the wedding dress fabric or skin textures would look "processed." In some cases the "smearing" was almost as bad as what I see in small-sensor digital cameras like the FZ50 I use for family and vacation use. NOT that big of a deal at all in the final prints, but annoying to see in images from expensive DSLRs.
Price/performance ratio -- Sure, great performance and lens selection ... but overpriced for the bottom line. I am a working photographer. I have to balance expenses with income and still have enough to pay both business related bills and my household/family bills.
Bottom line, I did some great work with the Canon gear last year, but I wish I had just gone from Nikon and Fuji directly to Pentax.
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