Just a comment Mike....

I'm trying to think back when I first came across the number system, and for me it was about the mid to late eighties.

A guirtarist who I worked with was also a very good session muso. Couldn't read music and played by ear, but would notate in numbers. That was in New Zealand. And he got all the gigs too.

So I guess it's been around for a long time. Who needs to read music properly if you know the reationship between notation ?

As you point out, you also need to improvise well and wing it occasionally, but it makes for a better overall player I think.

cheers, niteshift