I think I'm one of the few people who thinks that aestheticly, 25 is not the best design. That notch just breaks the flow of the beautiful Sebenza spine. The transition done on the past Sebenzas has been perfect. I'm also am not a fan of the finger grooves. For my hands, it just put the tip of the pocket clip straight into my palm and create a hot spot as well as making the knife feel smaller than it should.
Now, I love the new features on the 25: massive pivot, ceramic ball on lockface/detent, and the new large hollow grind wheels that gives it some flat grind features. Take away the notch and the finger grooves then I'll own a 25 again. Until then Umnumzaan will keep me happy.