Not sure on what board is right for me

Yeah it’s a bit confusing I think because Torstein has 2 pro models for 2013.

This one, which is the Mega

and the Ply you linked above.

yeah sweet, they seem to be the only one’s calling it out as Horgmo’s Pro model that I seen then. Definitely his kicker and powder board and the Ply will be his Jib board. I’m still after the ply as an all round park killer - I don’t think the flex between them is going to be a lot but will be too much to want to take it on rails. Wish they had some better sizes closer to a 55 though.

Is 153.75 a noticeable step down from a 156?

Yes. It will be noticeable, but that doesn’t mean it’s a bad thing. The 156 will be faster (speed wise), more stable, but stiffer, and slower edge to edge/turn. You might not notice all of that, and that’s not everything that will be different, but you will definitely notice the difference overall.