+1... You weigh the same as me, you're taller than me, and I'm riding a 159 Burton T7. I hate to say it cause it sounds like you want to spend money on a new board, but your existing one sounds like the right size and shape/flex etc. for the type of riding you want to do.
If money's no object and you want something light but still cambered and almost as stiff as your Custom, get a Vapor?!?
I looked into the Vapor as a replacement for my damaged T7, but it's not nearly as stiff as the T7. And I'd go with a Custom X but I'm trying to stay with a synthetic core of some type.