The issues seem to be multiplying here. So, again, let me just give my perspective on a couple of points.
First, I like to keep my files in Gray Gamma 2.2. It's, in effect, a subset of Adobe RGB, which is what I shoot in. The fewer transformations, the better. I think it's the best standard there is.
I used to think the compressed shadow valued of Gray Gamma 2.2 were a waste of our (then 8 bit) grayscales. I no longer think that. The compressed shadows make the print much more tolerant of major lighting differences. In particular, with my glossy gallery brochures, they look good inside as well as outside. Inside the 95% and 100% look the same -- totally black. However, when I take a brochure outside into the sun, I can "see into" that 95 - 100% compressed area.
So, for me, the compressed shadows make sense and work.
Second, regarding image adjustment curves, these are Photoshop curves. I use these all the time as part of my basic working-up of an image. I usually do not use them directly for printing, but they can be. At least with my inksets I can have a warm and a cool area within the same image via selecting different areas and applying different curves. This is a trick ICCs, ABW, and QTR cannot do. See for example http://www.paulroark.com/Whalers.html .
Usually, however, I use these curves to make an ICC that controls the print tone. The ICC is pulled into the Photoshop Print screen, not the Epson driver.
As to the Epson driver, I virtually always have that on "no color adjustment." (I think this is something Mac no longer allows, but I'm Windows, probably more due to history -- former day job necessity, etc. -- than anything else.) The Epson driver has to be set to the paper type (sets the ink limit, among other things), quality, etc. that was used when I made the ICC.
Paul