Couple of questions:
1) Are the Canon profiles made for the 8 bit operating system level print driver or the 16 bit plugin? The reason I ask is that Michael stated the gamut is increased on profiles made through the 16 bit driver.
2) Are the profiles you are comparing made for the exact same paper?
3) Do you know for sure that the profiles for the Canon were made with the optimal Media Type (a setting in the print plugin or OS driver)? It has been reported that different Media Types lay down different amounts of ink, and that using the wrong Media Type can affect the gamut considerably.
I haven't made any profiles yet, so can't comment beyond these questions.
Actually, I was using the generic profiles listed in the profiles links section of your Wiki, such as the Crane and Inkjetart profiles. I only compared profiles from the same source and the same substrate, Epson vs Canon. For example, the Crane Museo Silver Rag profiles show a much more saturated crimson for the Epson K3 printers than for the Canon iPF5000. There is no amount of tweaking that can get crimsons using the Canon profile to look like the Epson.
Beyond that, I can't answer your other questions, since I don't know exactly how the profiles were produced. I have noticed, though, that the Inkjetart profiles show far less of this problem. Which makes it hard to know which is a better preview of what I'd be dealing with if I got an iPF5000.
I started investigating this after I read a comment of Neil Snape's where he mentioned that Epson maintains an advantage in areas of dark gamut. I'm in no way affiliated or loyal to any company as yet, since I'm yet to purchase a pigment ink printer, but, as I mentioned, my art contains a lot of saturated dark tones, so I figured I should try to get a handle on this before making a purchase.