A little late to this, but here is my take on it.
IMHO I would never concider the level of comments that Jim put in his example, even if the end user aimed at was for novices.
I have two reasons for this. One is at that in real life, with this level of commets I think I would never actually get any LabVIEW written and the second is that I do not think it is actaully going to help Novices, who need to get to a situation where they are comfortable with LabVIEW primitives and the general look and feel of G code.
Somebody new to LabVIEW would just quickly read the comments and miss what the actual G-Code is.
I am very much with AQ in the idea of peer review, if the person reviewing the code needs an explination then a comment is definitly required.
Line labels are good, if lines travel a long way across a screen, sensiable labels for while and for loops can be very helpful as well.