I have heard almost nothing but good things about XM 10K SE bulbs.  They are a very crisp white, and make ushios look like iwasakis. 
 
Although I'm not sure on coloration, I am pretty sure that a higher PAR will yield growth in your corals (especially SPS).  I would choose that supplemented with actinics because a 20K bulb loses it's PAR alot more quickly than a 10K. 
 
Anyone can correct me if I'm wrong, but this is my research. 
		
	
		
		
		
		
		
	
		
		
	
	
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