I think the key phrase in this is "installed as Class 1 circuits." This, as you point out, would require the use of an article 300 wiring method.
I can't imagine why someone would want to just go out & change & existing Class 2 or 3 installation, but there are plenty of times in new work where going to Class 1 makes sense.
This issue was posed at an IAEI chapter meeting several years ago (can't remember which chapter & when) & the response was split about evenly.
If the entire installation complies with Class 1 wiring requirements with an article 300 wiring method, I don't see the hazard that would be introduced. When I see an article 300 wiring method, I presume I'm dealing with at least 120 volts. On the other hand, I have seen lighting outlets wired with doorbell wire and telephone wire. What a surprise that would have been for someone if they cut the cable!
Don, sometimes I think the new code books should come with a deck of Tarot cards.
[This message has been edited by Tom (edited 01-01-2002).]