Here is an older post in which Mark/DAGuide says one of AB's pics is the Imagejet for darks.
Here is a search that might yield more info on the paper:
T-Shirt Forums Search Results
One way to find out for sure what the differences are, and the best way imo, is to order the sample packs, and use each paper with your ink. Wash/dry them, and see what you think.
There's no substitute for seeing something with your own eyes.
As far as wanting to avoid a paper that is just a bad choice, I rarely see posts on Imagejet Dark. I don't know why that is, but the long and short is, I don't even have other posts to direct you to, other than that general search for the paper name. Anything positive or negative might be in there. ?
Good luck to you.
