Puggo - Jar Jar's Yoda said:

Question - would a properly upscaled master released anamorphically exhibit better playback on modern DVD players? Just curious.

It isn't the DVD player that matters, i.e., they will all playback either 4:3 or 16:9 DVDs without issue. It is the TV that matters. For a 4:3 TV, 16:9 DVDs are of no benefit whatsoever (nor do they do any harm). They will display exactly like a 4:3 DVD, with the exception being that only part of the letterboxing will be hard-coded into the video stream, while the remaining letterboxing will be generated by the DVD player (as opposed to all of the letterboxing being hard-coded into the video stream on a 4:3 DVD).

If you have a 16:9 TV, then a 16:9 DVD will fill the screen properly as-is, and you will get whatever benefits come from increased vertical resolution in the picture area (which is no benefit at all in the case of converting the GOUT or its masters to 16:9, because the increased vertical resolution in the picture area would just be artificial upscaling). The only possible benefit in terms of picture quality would be if you used a resizing filter during the re-encode that you know gives better resizing results than the results of your DVD player's and/or TV's zoom function.

The main benefit is convenience however, i.e., as I said, it will fill the screen properly as-is, like so:

While a 4:3 DVD will get "windowboxed" as-is, like so:

And you have to zoom in to get it to fill the screen properly.