@Bill Burk Thanks for the ping.
@F4U While I don't know the answer to your question, as chance would have it, I have with me a throw-away roll of Arista EDU Ultra 400 that I shot specifically for the purpose of testing it with D23. Right now it's late for me, but if you are willing to wait a day, I would be happy to the test with D23 straight at various dev times and post the results.
Let me tell you what's in the roll:
On a bright sunny day I went to a plaza and shot the same 6 scenes over and over for an entire roll. The camera is a Pentax 17 so I'm trusting the camera's internal light meter. I shot each scene twice: once at EI 250 and once at EI 160, then I moved on to the next scene.
I actually did this for 5 different rolls of film, but Arista EDU 400 is one of them, and I was planning to develop it this week. What I've been doing is I cut the film into 4 pieces inside a dark bag, and then develop each piece separately.
If you look at my post history, you'll see a post where I tested AristaPan 100 with 4 different developers. Later tonight (if all goes well), I hope to make another post where I test Kentmere 200 with D23 1+1 at two different times.
In any event, I had originally planned to test Arista EDU 400 with D23 1+1 for a few different times, but since your roll is pretty important, I wouldn't mind testing it with straight D23 at different dev times and then post the negatives here. As I said, it'd have to wait till tomorrow.
EDIT: I just remembered that the first few shots were accidentally taken at the wrong EI. So I only expect to get 3 good pieces of film that have all 6 scenes in them --- of course, I can cut smaller pieces and let the scenes be a bit different from piece to piece.