Like others have stated, I'm not interested in the conventional flipper design, but I've owned a couple Burger Knives EXK1s with the front opening design and was very impressed with them. I rarely flipped them open, but it was effortless to do. In fact, the South African front opening design might be my favourite one hand opening design to date.
As I mentioned in a previous thread, I think this lip-opening method would serve the Mnandi/Sebenza platform well. Easier to manufacture without thumbstuds/nail nicks to boot.
The Shamwari (Gareth Bull custom) is a lip-opening homage to the Sebenza. Jason Guthrie's Barlow is another that I am very attracted to.