*edit* I lost this on my last post...hungry baby interruption...
I have 3 micron, 1, .5 in SiC, BC, and CrO, and tried them on smooth and rough leather, as well as balsa. Nothing works as well as .5 CrO on leather, but I have yet to try Dave's spray. If you put a knife through the 3 micron on rough leather, the 1 micron on balsa, and .5 on leather, you will have an edge that pops hair with little to not sensation(though this works like crap for straights), and will run all over the place. I took a kitchen knife through the paces like this and it would fall through paper, and then slip on a tomato and bloody near take off my finger(lost half a nail).
I now skip grits. Cheap knives I'll set it up on a 1k, clean it up on a 2k, and strop on .5 on leather(sometimes the 3micron rough leather), cuts like crazy--just gotta be careful about deburring. My work knife goes up to 5k, strop on the 5k, then .5 on leather.
I rarely use the rough leather(it can round edges pretty fast) and the bare balsa is slippery and easy to screw up on without knowing it. Leather seems the best. Different types of leather, I don't know. Can't wait to see what Dave's got, because I'm happy with the Tandy leather I got, and his required a cross-country search.