I have Karve SB F plate and OC E plate. I find that OC E plate provides me with closer shaves than SB F plate. Noe I need to try OC F plate.I have the Karve F OC and SB plates. The OC is smoother and the SB is milder. Full disclosure, the only SB I’ve kept is my Charcoal Goods. I haven’t decided if I’m going to try to trade my F SB plate for a D or E OC, or just sell it. I have the same opinion with the Blackbird. The OC is smoother, but is also more aggressive than the SB. The SB is probably a better candidate for daily shaving. It’s still more efficient than most razors though.