Board size change

Shorter board is going to turn quicker edge to edge, will not feel as stable when you are riding faster, and will not float as well in powder.  If you find it difficult to turn your board because it's so long, you will probably enjoy riding a shorter board.  However, since you are used to riding a 163, I would try riding a shorter board before I decide to buy one.  Since you're used to riding such a long board, you may prefer something in the 57-59 range.  It's really all preference, and it depends on what type of riding you want to do.  If you want to ride a bunch of park and practice pressing it and doing rails etc, you may really like a board in the 155 range.

Do you also ride a wide? Are your feet size 11+? I'm 5'8" and also 150lbs and I ride a 155 and 157. When I started, I had a 148 and I just felt like the mountain was pushing me around quite a bit. Definitely helped me learn how to turn/carve though given the shorter length.

I think for a freestyle board, with my height, 153 would probably be ideal, maybe 151. For you, I would consider you to be on the taller end so I would go a size up from your recommended 155, so 157 or 158. This length would probably serve you a lot better in the park and groomers vs taking it out on POW.

If you've grown accustomed to your 163, especially with that list of tricks of yours, then maybe you can just go a bit shorter to help with adding more rotations, but don't jump too many sizes down. I'm with Spenser, try to demo a shorter board first or borrow a friend's before buying.

Definitely a shorter board for ya.  Don't go too short though.  I rode a board that was a little too big for me earlier this season, for a few runs, and I could definitely tell the difference.  The longer the board, the more work and power you have to use to turn it.  The shorter the board, the quicker and tighter, more playful turns will be much easier.