In all sincerity, i would like to see you someday visit Nineteens with the same vigor and intent with which you have explored the small format VOT system. I think you bring new, unique, and useful insight to the table, and could likely help take the Nineteen system to a level that has not yet been explored. I also understand that you have your hands full and such a journey with Nineteens isn't possible at this time.

A few points that should be considered about the model Nineteen system and it's proper components:

The 416-8B woofer, and 802-8G compression driver were the latest designs from Altec at the time. Both used newly designed magnetic circuits, and the compression driver used a newly applied phase plug as well.

Those are the components that the Nineteen system was engineered around, and for any real world comparisons, or improvements they are the components that should be used as they differ somewhat parametrically from other variants. The 416-8B, while not so well suited to horn driver duty as the 515 series, is a wonderful woofer by it's own merits, and can yield excellent results in other enclosures as well.

It should also be noted that the Nineteen enclosure is not a simple bass reflex box in that it was Altec's first use(to my knowledge) of a bass reflex system incorporating an additional resonant chamber/volume separated from the main chamber by a "throat".