I just got the Arca-Swiss D4 myself. It is a fine piece of gear with a smaller profile than the Manfrotto, which is one of the main reasons I bought it, but it is three times the price of this rig. The geared pan on the Manfrotto is a nice touch as well.
Hejnar isn't copying RRS anymore than RRS is copying Kirk. I talked to Hejnar when I ordered this piece (I profiled him on a blog I used to publish) and he is an interesting, hard working guy making good gear at reasonable prices here in the USA. I commend him on his efforts.