I've read and digested now :)Since you're starting to write larger GP extensions, let me suggest an alternative work flow
The class browser technique looks very interesting and I'll give it a go (1st issue I have is that it starts off small and has to be resized and moved - it would be VERY nice if it started off at just less than maximum height of the GP window :) )
I converted to instance vars/methods by doing exactly as you suggested - exporting the class and then modifying it with global search replace (and I wrote a little routine to make sure the instance vars were created as they work differently from shared ones
As you note - it is possible to make syntax errors (and I did) but eventually after a few iterations I sorted them out :)
I'll convert it back it again - I don't want to distract you from doing the big stuff :) and re-upload when done