they had one on photokina this year. it was connected to 5Dc. it produced some nice testshots for me. the zoom-by-wire is not fast though, it has a lot of glass to move inside that barrel! and the AF speed was also only okay-ish. definiteley not zippy. but again, we know why 8)
I guess it could be very nice for video work. any demo videos out there of it? 500mm f2.8 should get you a nice subject/background separation not seen on video before...
douglaurent, you should put these monsters on top of HeLaBa in Frankfurt and take cityshots at dusk/night...i think that would instantly deliver awesome pictures! greetings to nearby-frankfurt from frankfurt!!!