Doug, thanks for the extended and technical explanation. Wow, not a lot of 'white' in your transformation of those 14 balls! I am definitely observing some banding (especially cyan, but significantly in the darker / lower magenta, red, and to some extent green balls. As for a printer test: I will have to try the Adobe utility (assuming I have it or can download it for free: I have Lightroom 6 and PSE 14, but not full Photoshop). Presumably (please correct me if I'm wrong) printing balls that go 128 in to 255 and 127 in to 0 (or whatever for the number of bits) without any color profile will just make the printer show you exactly how far its gamut can go in KCMYRGB.
I'm still learning a lot here. On the one hand, I guess I should be happy that the printed 14 balls look very much like what I see on-screen when I convert to the printer+paper profile. On the other hand, I guess there's no cheap and easy answer to print those saturated bright greens. Tonight I made some little prints for my younger son's school project on Montana. One was a picture (I want to say from Wikimedia?) of mountains in the distance (what he wanted to show) with bright green grass in the foreground and a lake in between. He commented, totally unsolicited, on how the lake water looked a bit gray (on screen it looks more a deeper blue). He is nine years old, and knows nothing about color except what is in a box of crayons. I noticed the somewhat muted greens in the grass. I guess that's just what an R280 can give you.