The Dboys and Echo1 SCAR are the same exact gun made in the same exact factory. The only major differences are the following:
-Echo1 puts a lighter spring in it
-Checks shimming
-Slaps a warranty
It is up to you if the warranty is worth it, but they give it a once over for quality control.
They are the same exact parts though.....
As far as the rifle goes, I held it and shot it once and it was a very nice rifle for the money.