In general if you are using it the way its supposed to be used meaning the concave side towards your skin at all times it is more challenging to use. I find I can almost never get BBS on my neck because I simply can't go E-W across my neck with a western razor and angles don't work either but with the Tosuke I can go E-W because its a shorter blade and much more maneuverable and I do get BBS on my neck with it and the Iwasaki all the time.

I think japanese razors require a radically different honing method than western razors and while using western methods might get them sharp I wonder if the edge is being modified of course if you use the razor on both sides it won't matter but to do it correctly you do need considerable pressure when you hone.