I think you might get more hits if this were in the main reef forum, so I hope you don't mind, but I'm going to move it over there. 
 
As far as your question goes .. I thought, generally, XM bulbs had a more favorable following than Coralife, but, things may have changed since the last time I looked into it.  I have a XM bulb but not 400W (so not an apples to apples comparison for you, sorry), I use it on my 20g.  I would rate it "Ok."  Basically not bad for what I paid for it.  Never used a Coralife lamp, so can't help you there. 
		
	
		
		
		
		
			
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				 -- Tony 
 My next hobby will be flooding my basement while repeatedly banging my head against a brick wall and tearing up $100 bills.  Whee! 
 
			 
		
		
		
		
	
		
		
	
	
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