I just tried on an 80 min. video using the DVD Architect 24p NTSC Widescreen video stream template (23.976 + 2-3 pulldown).
When I rendered this out using a custom DVD Architect NTSC video stream template (VBR of 8,000,000 7,200,000, 3,600,000), the file size was 4.03 GB (4,333,539,328 bytes).
Using the 24p template and the same VBR settings, it came out to 3.37 GB (3,623,215,104 bytes).
Assuming my math is correct, this is a 16% file size reduction.
BTW, where do you get a 24P progressive setting setting in DVDA?
I fed it that file and it said OK and rendered it.