Call it a personal vendetta against magnetic ballasts and to a lesser extent, HID lighting in general. The blasted things have cost me a bloody ransom in power consumption!
Your very best bet in HID lighting right now is the 315W CMH lamp running on a Philips low frequency digital square wave ballast. It's actually more efficient than most of the blurple LED panels sold, and it gives up nothing in terms of spectrum quality.
If COB LED is outside your price range or comfort level to DIY, they're the next best thing.