There has been considerable speculation that due to an error in testing
or data recording/collection/editing, Kodak may have published times for
the wrong dilution of some developers with the new 400TX -- especially
HC-110, where it's widely believed the published times are closer to
correct for Dilution A than Dilution B.

My recommendation?  Forget it's a "different" film, and treat it like
old TX.  The difference between TX and 400TX in most developers is less
than variations you'd introduce without realizing it, like changes in
agitation, one-degree differences in temperature, etc.

And in the end, the times you get anywhere are just starting points;
I've had to cut my times for TMY by almost 50% from most published times
in order to get normal negatives.  The only way to find the times that
will give *you* the negatives *you* want is to test for yourself.