Just wait for reputable vendors to start putting out products using the Cree Horticultural Reference Design:
http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/XLamp-Reference-Designs/HorticultureReferenceDesign.pdf?la=en
The reference design has been constructed with the goal of 1k HPS replacement using LEDs and comes in at roughly 50% power usage for a similar density of light.
Cree is recommending to use discrete emitters rather than the CoB emitter setups many promote here. It is probably the smarter idea to go with what an LED manufacturer recommends rather than the suggestions from unqualified posters on public forums. The vendors here apparently don't even properly test their products and only use spreadsheets to determine performance. Any evidence they provide is anecdotal, highly subjective, often using non-relevant measurements and qualitative references that are completely unscientific.
You should always check to see if the vendor has the proper certifications, undergoes any third party validation testing (or even at least test themselves) and is financial viable as an entity to be able to handle warranty and liability claims.
Aside from the safety concerns from faulty manufacturing, non-certified products may cause significant problems with insurance in the case of a fire. Good luck explaining to an insurance adjuster about how you got the faulty grow lamp from some fly by night vendor pushing product on a pot forum.
