Why only the Omatic boards? Okay, well, I don't know too much about Omatic Boards, but I think of the three the Boron is more towards your all mountain style, but I think the other two should be fine, too. If you want all mountain and butterability, look into an all-mountain rocker board. Something to consider from Omatic is the BST or bowed surfaced technology. It's kind of like the TST from Battaleon, go look it up for pictures and how it works, but it's kind of like rockered or curved side to side (more this way than, say tip to tail, sorry i'm probably butchering this). It should allow you to butter really easily. As for stability and which boards this tech is available on the Omatic line, i'm not sure. Like the Extr-Eco with BS, seems like a park board, dunno how stable it runs all-mountain.
Edit: yeah go with a 157, seems like a good all-mountain size for you, keep the 150 for boxes and rails