One thing that is being overlooked in this 3 v 4 argument is PS. Three rebels of the type I posted will almost certainly kill one of your four ships before you shoot back. That makes it 3 vs 3 and then I have the higher PS next round again.
This is not theory. I've flown that build over two dozen times against all types of list, Imp and Rebel and lost only once to Han and 2x Blue B and that was with the HWK going down to the last B with 2 Hull left.
Not discounting your experience, but I don't see many three fighter lists recommended and I think they've mostly disappeared from the top tables in competitive play.