Support BladeForums! Paid memberships don't see ads! I've noticed that O1 stains easier, but no other real differences. A2 goes mostly grey, O1 takes on a whole lot of different hues. Both sharpen up easily and the only issue I've had with edge stability is with an A2 Bark River Northstar (one of the first) which had a very very thin zero convex grind (no issues after I ground it a bit thicker). Given a choice of the same knife with optimal heat treat, the same grind etc. I'd go for A2 since it does corrode a bit less, especially after a patina has formed.