I have a couple of Spyderco ZDP-189 knives and I’ve learned that the edges will chip if I use any stones lower than 600 grit – and with my Delica 600 will do it too, especially with edge-trailing strokes. ZDP is supposed to be hardened to about HRc-64, according to Spyderco. Rockstead claims to harden it to 67. My experience is limited, but I’ll guess that the chipping is a steel-dependent thing.
I switched to edge-leading only several years ago where I’m touching the apex. For re-profiling, I watch how close I am to the apex, checking with the ‘scope every 20 or 30 strokes. If I can see that I’m clear of the apex, I may use scrubbing strokes to remove material faster.
