For sure, you may get your knife very sharp on a 1200 stone, no doubt about it -- besides some special cases of steels that require careful abrading of the burr. But you don't want to maintain it with that 1200 grit or you will lose alot of material and the blade will get very thick behind the edge.
Believe me, after a few sharpenings it will matter, I'm afraid. When you're used to sharpen your own knives you may easily correct. No good idea for a novice sharpener who should stay with an existing geometry, unless there are good reasons to change it.