If you are just learning, you should probably practice on a norton fine india stone. More forgiving than a diamond. Diamond hones are better suited for coarse work.
It will take a lot of practice to get in the groove, and an india stone is cheap and will last forever. More practice for your money, and it is capable of sharpening about any knife to perfection. Plus you won't wear out your diamond hone, or all your knife blades practicing.
I've used the DMT hones quite a bit and like them, but they do take off a lot of metal, and they will wear out eventually. I've tried all sorts of stuff, but mainly I use the india stone for most jobs. If you get the 8" combo india, you can use the coarse side for heavy work too. If you learn on that, you will be able to do awesome work on a diamond stone, but learning on the diamond can make you think you are doing real good when maybe you aren't.