Cool, I was able to look it up with my iPad.
http://www.manhattanreefs.com/lighting
Phoenix on typical electronic ballast has a par in the mid 70's
Ushio 10k has a par in the mid 60's
XDE 10k has a parin the 90's
I am really surprised the Ushio is so much lower than the XDE, and is about what the 150 watt is. I hope it is just my iPad not working the sight correctly, I cannot imagine a 250 watt 10k being that low.