It's definetly different but it seems to be a common practice in the San Diego area from what i see. It won't be good if the arms sags too much and the wire runs out of slack though.
I think they must be, I can't see what the reason behind using them is if they aren't a lot cheaper than say the 125 or OVD, thankfully they don't make any small 400 watt FCO fixtures so they are stuck with using OVFs instead. I do see the occasional 125 installed as well, I think it is up to the contractor to decide what they use.