I agree that he's not ahead of Pattinson/Starc, but he definitely offers a point of difference in his bowling. That being said, despite Marsh not being a top 6 bat and his Test average only being marginally higher than Starc's, I think to say they are of comparable batting ability isn't true at all. Starc is a decent lower-order batsman that just loves to go out and hit the ball as far as he can, whereas Marsh has a genuine batter's technique and application.i'm not sold on marsh playing #8 as a 3rd quick though.
he may well be ahead of siddle these days in the bowling department but not ahead of patto or starc (whose batting is actually compariable to marsh).