IMO, yes they are a very good brand. I have 2 250w 10k's and they each put out 530 PAR. Only Iwasaki put out more par. Very good value, I love em personally. http://www.cnidarianreef.com/lamps.cfm
I have used the Ushio 250 watts and the XM 250 watt, both the 10,000k. There isn't alot of difference in the color, but with my ballast the XM bulbs give me better PAR.
Thomas