nice, very nice . I've got a pair of Open 4CD's on Ultegra/600 hubs which I really like & I found standard pads worked fine but I've also a pair of Open 4 Ceramics on Dura Ace 8 speed that are now on my touring bike (because I can..yay me) however I'd love a set of Mavic 571 hubs...absolutely gorgeous.....
Any brake pad for aluminium rims should be ok, the grey anodising will wear off with use in any case, and I believe that the braking performance is actually better once the anodised coating has worn off.