Bicycle production/sales figures?
I can only answer on the second bullet point of your question:

...may have more rants/raves/discussions on web forums...


Instead of infering this by the production count, you can directly find out how much discussion is happening for each particular bike model.

A simple way is to use Google. For example:


https://www.google.com/search?q=schwinn+letour gives "About 43,800 results"
https://www.google.com/search?q=schwinn+voyageur gives "About 705,000 results"


That definitely means that you'll find more written material on the internet about voyageur than letour.