I haven't cut a lot. But I've cut enough to know that you're still gaining usefulness. Dare to compare: hand-cut pearl, traced on to wood, and then hand-cut cavities. How can that be more accurate than hand-cut pearl, followed by actual cut pearl transfered to a 'program' (or whatever the terminology is), and then cut into the fretboard automatically, based on that scan?
You're likely going to get more accurate results with the machine, and if not "more" accurate, you'll still be in the same ballpark while saving yourself some aggravation and fiddly work (by comparison, praying that your chisel or Dremel doesn't slip).
.005"-0.010" isn't precise enough for some fretwork, but it's plenty accurate for all but the most intricate inlay. Let's put that into plain english: "five-thousandths (one-two-hundredth) of an inch to one-hundredth of an inch". That's a barely-visible line, which I would be enormously pleased to achieve with hand-tools. More commonly, there will be even larger gaps than this, and the CA or epoxy will fill it in, leaving the appearance of invisibility. The crap-assed amateur inlay I've done had far, far larger gaps which still ended up looking "meh... acceptable". But that's a different story... because if you can achieve 0.010" accuracy, you're well beyond the "acceptable" range and well into the "sweet"!
All that said, it still hasn't even been assessed that the thing won't cut pearl. It well may. Though, I can't imagine it'll cut it without a godawful "burnt hair" stench and lots of harmful dust.