Talk about what steel is better, especially on folders sure produces some interesting comments/observations. Clearly it's a VERY subjective thing.
Since this is a very old thread, I won't answer the OP directly. Going back to a thread I started (& others have some similar, of course) about what steel is enough, especially for folders, it amazes me there's much talk about "toughness." On a FB, yes, for a folder, both that steel must chip easy &/or is being abused. It's possible, but probably doesn't occur much.
I have not had a Seb in BG-42, but I've had a few different folders in that steel (Including a Lightfoot custom). I can't say it's edge holding was any better than S30V, but that's me. It didn't seem worse, but not better, either.
I certainly haven't tried everything, but the steels that were noticeably better at edge holding were: M390, M4 (By certain makers), & ZDP-189. I'm sure some of the newer ones are noticeably better, but I wouldn't know.
I think on the BG-42 Seb issue, if it's a good deal, it's probably worth it to get it. They certainly hold their value & high on want lists (Especially among Seb owners) & the steel is very good.