What developer did you use? I dont have a densitometry, I use a ringaround to determine my E.I or personal ISO, you seem to get more speed from 400 action than I do and I've used a lot of developers, best I get is 320 with MCM 100, with D76 or HC110 I get 200.
Great article. I, too, informally compared a few films, namely TMAX 100, Provia 400, XP2+ and Colorplus. Just like you, I came to the conclusion that, apart from having vastly different exposure density curves, grain structure, spectral response, response to colour or lack thereof, and favourite football team, there isn't really much of a difference!
Thanks for sharing. The 100 and 400 curves look essentially identical. If developed to same density they would be very close. The 320 looks pretty under developed here so hard to conclude much. The 200 is the clearly different film, which makes sense given that it is a totally different formula from the other two.
Try the 400 in medium or large format exposed as per manufacturer's curves in Excel 1+1. Pretty unique spectral response, really interesting film, quite different from pretty much anything else currently in production.