Dave made the correct identification; the knife you're talking abotu is a 250 sujihiki. So that's a double bevel slicer, not a single bevel yanagiba or sushi knife.
As to how practical it is to use it as a main knife...well... it seems to work for him. I've been meaning to try it at some point but I haven't gotten around to it yet.
There actually are some advantages if you're willing to settle for low blade height. There's less drag and less place on the blade for stuff to stick on, so it works quite a bit better for food release. At this point I actually use my Ashi 210 petty (which has a suji profile) as my main knife for cubing potatoes.