I used to use sand paper too, and thought that it was actually pretty good. But then Dave had a sale on atomas that I couldn't refuse and I bought one.
One of the things about really nice tools is that you go from thinking: "do I REALLY need to buy this?" to "how did I ever live without this?"
It's just soooo much better than sandpaper when it comes to stone flattening and makes even my least favorite part of sharpening enjoyable. I've had about a year and still still not noticed any substantial decline in stone-melting aggression. I can't imagine wearing this thing out anywhere other than a professional sharping setting.
I don't know what kind of magic paper Bobby uses, but I never got multiple good uses out of a sheet of 120grit w/d paper (However, some of my most-used stones are pretty hard). Maybe I just never felt like it was worth the extra tendinitis to grind away on sand paper that started to lose its bite or wrinkle & tear.
Someone told me that using diamond plates on steel will wear them out more quickly b/c what "wears out" a plate is loss / fall-out of diamonds, and steel is softer / behaves differently than stone and "pulls" the diamonds out of the plate. The diamonds seem to be really firmly bonded on the Atoma though, and I've used mine on knives to do edge repair, tip repair, re-profiling, thinning, etc and noticed no ill effects. However, I also use light pressure as it seems to cut just as fast and is easier on all parties involved.
And Theory: I hate you! You have left me with no choice but to go buy yet ANOTHER diamond plate (1200grit replacement) and make my 140 into a 2-sided combo... the idea is just too awesome not to do (even if a year ago I would have thought that it was crazy ).
