I'm short (5'6") but have an athletic build( lift heavy and weigh 158-163lbs). I have the original attack banana and love it. I went with the shorter board (153 i think) because I used to ride on the east cost US for the most part and like weaving through trees when I can. It was fantastic. Recently, I relocated to Thailand for work and have spend most of my time riding in Japan and a bit in New Zealand. The shorter banana has performed great in the deeper pow of japan but i feel like i have to work much harder when I ride. I'm still happy with my choice though, because I'll be back to the icy east coast soon and my board has performed like a champ. I like the feel of a shorter board even if it means working harder in powder. It will probably come down to personal choice for you, but I am a big attack banana fan.
It's all relative, how hard you ride, how much flex u want, I am the same size and I'd get the 156. If u want a stiffer ride get the bigger one. I've never rode small mid west mountains/hills but I think you could make the 156 do what u want.