I've been using Japanese Planes for about a dozen years now, maybe a bit more. I purchased my planes from the Japan Woodworker out of california -- they have a web presence.
The planes I typically use are two smoothing planes and a right hand rabbit plane. While I do believe that the Stanely series of Rabbit planes is much "better" at planing shoulders, I long ago gave away my Stanelys and have stuck with my Japanese Rabbit plane.
As far as the smoothing planes go, I rounded one considerably -- making it into a ver nice scrub plane. The Irons NEVER chatter, no matter how proud they are, and, after the first couple of years, no longer chip excessively. I have no complaints with my planes, though, I need to say that I am not as plane dependent as many (I generaly use them more for truing and planing boards and surfaces than for joinery work).
I love wooden planes, and heavy irons.