Nicely done adaptation of Gobin's Purple Spey.
The only thing you will find with marabou hackled speys is in faster water, the marabou collapses around the body. That is why marabou spiders are tied with a dubbing ball or ball of chenile at the shoulder, the ball keeps the marabou from collapsing against the body. Unfortunately, you cannot tie the exaggerated shoulder on a spey fly without disturbing the wing set.
However, in slow water, a marabou hackled spey works very well.