It's been reported that the Wing rotors are a direct fit. BUT: The Wing starts out at 3.5MM with a service limit of 3MM. The Valk is 4.5MM with service limit of 4MM. Big difference in price.
Sandy's got the numbers a little wrong. Valk original is 5mm and min. is 4mm, while the Wing original is 4.5mm and min. is 3.5mm. Having said that, I don't think it's a problem to run to the minimum Wing spec, as my original Valk rotors were below 3mm and still stopping fine (for the record, they were that thin when I bought the bike). We've only got about 8K miles on these Wing rotors with no problems so far. They are identical in appearance to the EBC replacement rotors, which is slightly different from the stock Valk rotors. EBC lists the same rotor for each application, but charges more than Honda does for the 1800 Wing rotors.