According to Larrin's most recent article on corrosion, the CF 20CV model should be fairly rustproof. I have two of them and they come just abut as sharp as a razor blade.
Spyderco Collection: Military (S110V), Bob Lum Darn Dao(CPM-154), Yojimbo 2 (1 in S30V & 2 in 20CV), Sustain(20CV), Native 5(Maxamet), Jumpmaster 2(H1), Province(4V). SHORT LIST: CF Shaman(S90V), Lum Tanto, Native Chief(?), Street Beat and Street Bowie(4V at 60+ HRC).