Just wanted to let you guys know that I was working on this last night. Here is the post from another thread:
I think I was able to arrive at the optimal solution with only some small edits to the code. I also improved some other small things in the KAP140 while I was there. The only thing I'm not sure about relates to the behavior of the real world unit. If you engage the autopilot when you are already within 200ft of your selected altitude, the vertical speed will be zero, and it will capture the selected altitude. All things considered, this is a very small tradeoff in my eyes, compared to what is sometimes required to circumvent the native autopilot. It's always amazing when you implement some of these small things, and you can immediately feel how much more intuitive they are. Thanks, guys!
An addendum for this thread: The capability to display "PIT" mode still resides in the KAP 140, but you should not see it during normal operation. I've left it there more as a debugging tool, since errant autopilot modes are my best tool for diagnosing GPS addon issues.