Upload & Sell: On
Honestly, if you have to have bare mounted ultra matte prints, it won't make a huge difference what paper you use. One might be a bit better here and another a bit better over there, but you're still dealing with a limited gamut medium especially when it comes to certain colors and particularly when it comes to darker saturated tones, where all the matte papers completely fall apart. You're just going to have to learn to live with the limitations of the paper or learn how to modify your files to trick the eye into thinking the paper is better than it really is - i.e. emphasizing blues can make the warm tones more effective.
I have one client I print for who loves Epson Hot Press Bright and we use a lot of that, but there have been times when it wasn't available in time and we used 308 instead, and I have to tell you, that aside from a very slight difference in the white point of the papers, they are remarkably similar print the same file to each paper. I mean, side by side, they are almost indistinguishable. I've even interchanged profiles by accident and the prints were fine as well. Could very well be that Hahnemühle makes the Epson paper with a different base than their own. The one advantage of trying that is that Epson's own proflles tend to be very very good, while Hahnemühle's only so so.
I've been making my own custom profiles for close to fifteen years now. Maybe it's fourteen, but somewhere around that. You could actually use ICC profiles in Photoshop 4.0 for converting to CMYK, but it was 5.0 when the RGB conversions became available through the Profile to Profile command. I think it took a few versions to arrive at Convert to Profile. We started out using Praxisoft Compass Profile and the same Gretag Spectrolino to make custom profiles for the Lightjet and Chromira prints we were getting at the time. The labs had now idea how we were able to nail color on the first print. Compass Profile didn't work so well for ink jets and ProfileMaker 3 had a better profile engine for the very non linear Epsons of the period. ProfileMaker kept getting better and better but was finally dropped when the Gretag/X-Rite merger happened and further development was halted. Now we're using i1Profiler, which is better overall for RGB profiles but not nearly as intuitive for CMYK press profiles.
I've learned over the years that no matter what, I can always make a better profile myself than whatever canned profile I have available. Even for my friends who use ImagePrint, we improve on those as well. It all depends on the level you want to go to and how much that extra couple percent means to you. Maybe, if you have to use the papers you use, that little bit extra will be the difference that makes the difference. Only one way to find out.