I think Picaxe is a good platform in many ways, but if you hang around the forum for long you'll notice that half the threads are about getting around the platform's limitations.
For example most threads that ask "How do I chew gum and walk at the same time, all at 500Hz" usually get a response like "Use one Picaxe to chew gum and another to walk".
To be fair though it is I think appropriate for its intended audience, ie beginners and school kids, although I have seen some pretty reasonable projects using them.
BTW that's interesting about the gosub limit, I always assumed it was a stack depth issue and as few programs get 16 deep in nested functions I didn't see it as a serious limitation.
Rob