Evil D wrote:
Japanese sword smiths believed that curving the blade aided in slicing ability
I have no idea what their thoughts were/are. But, I think I recall somewhere that the curvature of a katana happened naturally through the forging or hardening?
This was my impression of it as well: the traditional swords all had some sort of what we would now call "clad" construction, and the curvature was basically a controlled warpage during the hardening. This, of course, may not be at all accurate, but it's what I had heard. Probably more likely that a few were made this way, and people liked them so the curvature was emulated even sans warpage.
To the question, I like a little belly on my knives, but don't like upswept tips. My favorite geometry is a low but consistent curvature, which is great because spyderco is fond of the leaf shaped blade. I find the belly helps with push cutting through things, and it may be in my head but it seems to cause me to use more of the edge. I find I get more consistent dulling with my bellied blades, my Yo2 tends to dull more in the first third of the blade (from the tip), but I wouldn't change it from a wharnie. Some of my favorites: R, Delica, Sage/Manix/PM2, PPT. Some that I avoid due to blade shape: Lionspy, manbug, Foundary.
Also, I'm going to disagree with blev a little bit, in that the tip/wrist angle is also dictated by the design. The Tuff for instance has a lot of belly, but the tip is kept in line with the wrist by the angle of the blade when open (see below). But in general, he's correct in that the more belly a knife has, the higher the tip is going to be.