The prior color patches posted were all for difficult colors with Baryta semi-gloss on the Canon 9500 II. These are the results for the Canon Matte Photopaper. Excluded were colors with L < 23 since that's the blackest the paper can achieve.
Canon matte has a much smaller gamut. To the point that there were no printable colors that were more than 5 dE2k outside of the Adobe RGB (1998) gamut. There were, however, a rather large number of colors that were within both sRGB and aRGB that, when printed, would be more than 5 dE2k off.
The takeaway is that soft proofing is important because so many colors are not printable in both sRGB and aRGB and this is more critical for typical matte papers with small gamuts.
These percentages are based on a dE2k of 2 or more.
Percent sRGB colors not printable on the 9500 II: 46.2
Percent aRGB colors not printable on the 9500 II: 55.7
Percent of extra colors printable on the 9500 II relative to sRGB: 6.2
Percent of extra colors printable on the 9500 II relative to aRGB: 0.1
These attached image is from colors selected by collecting all patches that print more than 5 dE2k off and were at least 10 dE2k different from each other: