Pfm I think do cast disks to replace stainless on Bmw's so that's where I'd look for cast disks. I deffinately think they have their place if you tend to use the bike in all weathers, though I just drag the front brake on almost pernemently if I get caught in a real downpour on the 500/4, onece warm the standard rotor works fine even in the worst Welsh / Yorkshire downpours, particuarly bearing in mind the tyres get less grip in those conditions and when I onece was on the motorway from Leeds in such conditions visabilit was also down to nil too. Brakes in standard form were still good for hauling a bike, sidecar and spare bike in bits and tools to put spare bike in bits all to a halt at motoway speeds - reduced speeds for conditions as I like to be able to stop on the amount of road I can see!