Diamond stones are the way to eliminate complaints about the sharpening difficulties with "super steels". Every steel sharpens easily with a good diamond stone.
My typical advice for folks getting used to diamond stones:
1. The diamonds will cut just fine without hard pressure and they are brittle and will break off more quickly if you push hard. Just let them do their work-no need to try to help out by applying a lot of pressure.
2. Diamond stones can often need a bit of a break-in period. I usually start off using a new stone with a beater knife or one I'm not trying to maintain with a perfect edge. Don't try to speed the break-in process by violating rule 1 or by rubbing it against another stone or diamond stone.
3. Diamond stones will wear noticeably when they are first used. Within a few uses, they will typically become noticeably less aggressive and smoother--this does not mean they are worn out, it means they are broken in.
As with any product, diamond stones are not all created equal. Some manufacturers are definitely better than others. In addition, there are two types of diamonds used in diamond stones (monocrystalline and polycrystalline). The information on the latter is complicated and there seems to be significant difference of opinion. I generally pick a company with good reputation for quality and buy their products rather than trying to pick a side on the mono-vs-poly battle.