It could be the profile, I seem to recall that in the past when I tried some of the Hahnemuhle ICC profiles I got really poor results in saturated darker colors, especially greens and browns. Creating a custom profile helped tremendously.
On my Epson 2400, the "ICM - No Color Adjustments" mode puts down way too much ink in the darker tones when using matte papers, and what happens is that the shadow tones become such a muddy mess. This isn't helped by the fact that GMB profiling software has a tendency to favor saturation over tonal accuracy (depending on the options chosen for creating the profile), and dark greens and browns turn all splotchy and cartoonish.
By using the "Color Controls - Adobe RGB" mode to print my test target I was able to get a much better ICC profile.
You can test whether this is the cause of your problems by printing without a profile and using Color Controls mode to see if you get better shadow tones. Of course, without a profile you may find that overall color accuracy is less than desired, but if Color Controls helps with the darker saturated tones you can always have a custom profile made using that mode.
The reason your ABW prints look better is because they're not using the ICC profile.
