I'm into those if I can find them (just dropped an email to them to see about stockists in Japan) but am not entirely sure about the price.
Ultimately, they may well be perfect for use and better quality than the usual Chinese/Taiwanese rims but they are also double the price of the 38mm tubulars.
I'd go tubular.
Lighter and nicer rolling on the way up, and carbon tubular rims are a far better idea for descending than cheap/light/carbon clinchers.
Try and Source these locally?
http://www.bikehubstore.com/product-p/wh133ul-2024.htm