I see that the Canon 1100 has a gloss overcoat and the Epson P5370 doesn't. Does the Canon need the overcoat on glossy media? And how well does the Epson handle gloss differential and bronzing without the overcoat? I currently have an HP Z3200 and use the gloss enhancer on glossy media.
Yes, the Pro 1100 (like the Pro 1000 that it replaced, even though it had a previous generation ink set) includes a Chroma Optimizer ink. Its use is up to the user, who can decide not to use it at all, to exclude the borders of the print, to apply it to the entire print (including the borders) or to set it on Auto and let the printer decide on a case by case basis. According to Canon, the CO is supposed to reduce gloss differential, reduce bronzing and increase contrast and maximum black.
To tell you the truth, I have seen less gloss differential on the same image/same satin paper when printed on the Epson P5370 (which does not have CO) than on the Pro 1100 (which does), but it is anecdotal evidence and maybe it was an isolated situation. Generally speaking, I tend to be very vigilant of highlights when I print on satin/glossy media and in those situations where there are uneven areas I tend whenever possible to switch to a matte paper to avoid the issue altogether.
So far I have not noticed any bronzing with the P5370 on any of the fine art PK papers that I use. I understand that Epson’s UltraChrome inks from and after the K3 generation have been reformulated and include technologies to minimize bronzing, including through the Black Enhance Overcoat feature, and they are supposed to reduce gloss differential too with no need for a separate gloss optimizer.
Whatever the reason, I am impressed by how well the P5370/UltraChrome Pro 10 inks perform overall.