Marine Fish used to have one of those fixtures in stock. Seemed to be very well build and study. Obviously very expensive. But, it was neat as the pods had some very limited movement, so as it says, you could kinda 'spotlight' corals,.
I'm not really sure why HID hasn't caught on in the (USA) industry. Must be some reason...
BTW< for the avid DIY'er, if you did want HID, you can get the ballasts and starters for fairly cheap (as car parts; new or used off of wrecked luxury cars) and then you might fab up your own design.