As far as i'm concerned the only thing that is important when it comes to using a knife is that it's sharp. Don't know whether any of you have had a go with a flint knife but my view on knives completely changed after using one. It was flint that a friend had knapped and to me it looked for all intense and purposes like a little splinter of flint. But carving with it was an amazing feeling someday i'm going to save some cash and go flint knapping with John Lord and may never use metal tools again! Ion Constantin looks like he is using a hacksaw blade stuck in a bit of wood and i've been told by Robin Wood that he sharpened it with a file!
At the moment i use a Frosts 106 for most of my carving. Previous to that i had been using a 120 which i had to make a handle for - after cleaving a tough bit of wood with it i twisted the handle right off! That said I find these swedish knives have the perfect handle for me, and i only carved myself a new one because the old one broke.
When holding the knife with a standard forehand grip it is more comfortable and gives you more power and control if the handle fits snug in the palm of your hand, i was teaching a four year old girl some knife cuts not so long ago and although she was quite competent she would have found it much easier if the handle had been shaved down a fraction so that she could close her grip. i don't really get all the so called ergonomic grips you see on different knives because i change the position of my hand quite frequently up and down the handle and in reverse i find a symmetric one very useful.
One thing that Ben Orford a tool maker pointed out to me is that with laminated blades people tend to make the bevel more and more shallow because the harder metal abrades away more slowly, i have found this to be the case with my knives though i do like the angle to be pretty shallow for softer woods. I usually tell people that the laminated blades are better because they are quicker to sharpen but i think i'm just repeating what i've heard elsewhere and is not neccessarily true. Fritiof had some 120's rehandled and a home made knife in hard steel (sorry i don't have more information than that) His short knives had large bellys this is something most people reduce by accident when sharpening. The belly of the knife is extremely useful for reaching the middle of large flat areas and for slicing cuts with a thumb push, and for getting into nooks and crannys. All people are differenmt and have varying techniques, i at present am still sold on longer knives, but Fritiof made the point that most of the wear on the knife is towards the hilt and when sharpening a long knife you have to sharpen the whole length which is harder to do the longer it is. When doing big powerful long slicing cuts i find i don't use the length of the knife at all, but i do use it on levering cuts and you get much further travel that way. Often when doing a reinfrorced pullstroke i have my hand all the way up the blade with my thumb in contact with the last inch or so, on a 106 this part of the blade is small to get around tight corners but also remains sharp for doing long finishing cuts. Fritiof had a knife with a fatter bevel for cutting knotty bits etc, this is a very good idea and i intend to do so now i can have a few more knives at my disposal. Especially as i usually find i'm sharpening because of hitting a knot and rolling the edge, i think having knives like del stubbs with the back of the blades rounded and polished is very nice for your hands but also good for pushing back knackered edges (always use lubrication!)
getting bored now, i will probably write more on this and try edit it so it reads better.
hopefully more photos on tumblr by end of day http://barnthespoon.tumblr.com/