Recently I purchased my first set of good bench chisels (Two Cherries) and my wife got me a set of #4 and #5 LN planes for my birthday. I also have a couple old pre-war Stanleys. I've been keeping the Stanleys sharp using scary-sharp and the Veritas Mk II. Faced with a full pouch of chisels that need initial sharpening, and the new planes, I headed out to a Woodcraft store a few towns over to pick up wet/dry paper in needed grits.
After grabbing the sandpaper I wandered about trying not to drool too much on any one tool or jig, before a friendly salesperson and I started up a conversation about sharpening which lead me to the bag now sitting on the floor next to me, containing four DMT 3x8 diamond plates
Extra Coarse (220 mesh / 60 micron),
Extra Fine (1200 mesh / 9 micron)
Medium Extra Fine (4000 mesh / 6 micron)
Extra Extra Fine (8000 mesh / 3 micron)
The concept was that they would be a suitable long-lasting replacement for scary sharp, which might have been an inexpensive way to start, but the sandpaper isn't cheap in the long run.
Now I'm not so sure about the Dia-Sharp Plates. A web search seems to indicate that folks use the diamond stones almost exclusively for flattening whetstones, and not for the actual sharpening, and there is probably a reason.
Advice much appreciated.