I use SIC stones on my Edge Pro to do that sort of work, Congress Moldmaster stones, they are VERY hard and cut fast.
I do have 2 Shapton Pro Stones for the Edge Pro, the Mold Masters cut faster.
+1 with your take on the Sic Moldmaster stones, they are very good, and 5cost effective (you can buy a pair that fit Sharpmaker [SM] for under $10 total). For folks using SM and wanting to be able to profile fast, including hard steels like D2 or those with high vanadium carbides, these will get it done and I see no better alternative for that specific role. Basically, the Moldmasters enable SM to become a complete sharpening solution for the first time. However, in my case it seemed to get best results if, after profiling on moldmasters say 150 grit, I switched over to diamonds (the Sharpmaker 400 mesh rods) to apex. That got my edges noticeably sharper in the things they could do slicing news print or shaving hair. The results with diamonds were noticeably better than if I just used the straight Moldmaster SiC progression such as 150/400/600, to profile, apex, and finish prior to stropping.
My sample size on sharpening super steels is small, just a handful of personal knives in S30v, S35vn, M390, 20cv, and CTS-XHP. What I've observed up to this point:
- You can definitely use SiC stones to work with these super steel blades. I got tolerably good results whether on Sharpmaker or bench stones, if I used Sic stones *only* for the coarse bevel setting and profiling work. I could also use Sic for the whole progression and get sharp, but it was a noticeably lower level of sharpness than when I used diamonds for the high grit part of the progression. Personally, I would *not* recommend trying to sharpen these super steels using ONLY SiC stones, even though I've demonstrated at home that you can do it, and it will achieve a decent working level of sharpness.
- The progressions that have ended up working the best for me on these super steels, where "results" are measured using the home sharpness tests indicated in the Sharpness Chart in forum sticky:
- Absolute best: diamonds end-to-end in the progression. Example: DMT XC (220) > DMC C (325) > DMT EF (1200) > strop.
- Very good (sharpening results that are nearly as good as (1) and totally usable for EDU knife tasks): Sic stones for the coarse/profiling work, followed by diamonds. Example: Norton Crystolon coarse (120) > DMT C (325) > DMT EF (1200) > strop. Another example on Sharpmaker: Moldmaster rod (150) > SM diamond rod (400 mesh) > SM UF ceramic rod > strop.
I wouldn't even try to pretend to offer an all-encompassing explanation for all this. We have some super experienced folks, in this forum and elsewhere, on both sides of this issue (you have to use diamonds to get optimal/best results, or, you don't--you can use other abrasives and get equal results). Apparently it's not easy to figure this out. All I can see is what I've observed with my knives, and that using all diamonds got noticeably better results on these steels.
But it also doesn't seem controversial to point out that 'other materials can work' (at some level of sharpness) to sharpen these steels. I've been able to get decent sharpening results on the steels I listed using combinations of SiC, Alox (the Baryonyx Arctic Fox stone), and even Spyderco UF ceramic as a light finishing step just prior to stropping.
The real question that seems interesting to me, and mildly controversial, which I've not seen conclusively answered with any testing that I've run across: Could you take a high vanadium carbide blade of at least 4%, say 20cv, or even S110v, sharpen it entirely with a non-diamond progression starting with a full edge profile all the way thru stropping (no diamonds or cbn can be used in the strop either 
), and get tested sharpness results that are as sharp or sharper than if you did the same thing with a 100% diamond progression? Same person, same blade, same sharpening steps. Only difference is all-diamonds progression, or totally non-diamonds progression--pick whatever abrasives you think would work best.
My hunch on that would be no, just based on what I've observed. Other stuff can work, but you have to use diamonds or cbn to get optimal sharpening results with these steels. But I don't KNOW that, and would be delighted to learn otherwise, as it would expand the range of sharpening stones I can use with my super steels.
Here's a small test (which would not 'prove' anything conclusively, but would be a useful data point) that I'd love to see:
* Recruit one of our established pro sharpeners in the forum.
* We all chip in and gift them 2 copies of the same blade with high vanadium carbides, let's say something in S90v or S110v.
* We agree on a basic set of sharpening steps and process, and we agree on two progressions: one that's all diamonds or cbn, one that's all NON diamonds.
* We agree on a sharpness test 'protocol' that will be used to evaluate sharpness.
* We find out which blade does best on the test.
* If we want to slightly increase the rigor of the test: we recruit TWO pro sharpeners here in the forum, and have them both run the above test so that we have a little more data.
I assume there are some others here that would be open minded as I am and just interested to try something like this and see what we learn. If anyone is interested, I would be delighted to chip in a few $$ to help fund the blades for the test.
. However it is one of my all time favorite blade steels for Spyderedges ( serrations). Few people remember how outrageously hard that steel was to maintain. 
