Sorry just now saw this as I don't usually get notifications for some reason. I've been carrying the small inkosi almost exclusively for about 8 months now, with exception of the few times I've tried to go back to a small 21 on occasion. I use it for any EDC tasks I have. And yes it opens one-handed with no issues and I've never needed to apply loctite. I've only cleaned it once in 8 months and the action has stayed smooth the entire time. My experience with carrying 21s was not the same and I usually had to clean them at least once a month or so.
If you think about the types of use for a small EDC folding knife, 90% of the time or more you are probably not going to be holding it in a full-on "hammer" grip, so the finger grooves on the small inkosi become a non-issue in practical use. It may feel small if you're just sitting around holding it, but I've never needed mine as an EDC and thought it felt small when I was actually using it for something. Not that the small inkosi can't handle it, but if I know I need something for heavier use I'm probably going to grab a larger knife anyways. As an EDC I want something that can tackle unexpected jobs while I'm out and about, but doesn't take up a bunch of pocket room.
When comparing the inkosi to the 21, either small or large, when fondling or just holding it I initially thought I liked the feel of the non-finger-grooved 21s better. However, after using the inkosis for a long time and going back to the 21, I now find the 21 to feel very "blocky". When comparing small to small, I've grown to prefer to aesthetics of the inkosi as well. I think it's one of the best looking knives on the market.