For "birding", 8x42 is the best all around size, and some birders like me also have 10x42 for open range and big water birds like hawks and loons.
As others have said, the optics have gotten radically better in recent years. All the good features and build characteristics creep into the picture with $200-$400 binocs, and IMHO you have most everything including exceptional optics in the $400-$600 range. The $2K binocs do get better, but not 2-3x better!
I went with Nikon Monarch 7s. The 8x42s have an exceptionally wide field of view which helps me locate birds better vs looking thru too narrow a tube to lock in on a bird.
--tg