JAF,
The Mikro in A2 @ .150" blade thickness holds up reasonably well to corrosion, but I know what you're talking about. I fish the VA tidewaters as much as finances will allow me to travel. Hence, we offer the Mikro II in Sandvik 12C27 @ .125" blade thickness. BRKT's proprietary heat treatment drives 12C27 to very respectable edge holding characteristics. Both blades are convexed, but sharpening is certainly not difficult, it's actually very easy to do. Here's a link to a decent convex sharpening tutorial...
http://home.nycap.rr.com/sosak/convex.htmM