Join Date: Jan 2007
Location: Sacramento, CA USA 96814
10 degrees BTDC is a pretty hefty idle advance so I don't know but I'm guessing your bike has fixed timing, and no mechanical advance. If that's the case, and a US spec bike has the same timing, then the two are equal. If a US spec bike is running a 6 degree BTDC timing, then you're already there and don't need (and wouldn't want) the aftermarket rotor with a 4 degree advance.
It's common for manufacturers to vary the timing on the same model for different countries due to differences in available gas octane.