Spent some time with my M4 yesterday. Damn good disc! Give it a small hyzer and it's the straightest disc I've ever thrown. 300 of the straightest feet I've ever seen. Thrown flat is works a nice S with a little fade at the end. Kicked my Comet out of the bag after one day.
For me there is room for both. I have a stable/turn resistant comet and a comet i use for anny's, the m4 is a faster version of both of those for me depending on the distance and ceiling.