thanks Jim for the info. I did purchase some Clayton Extend, so I'll continue to run some tests with that first.
I should clarify that I'm making my enlarged negatives directly from positive originals (ie Scala).
I have tried LC-1 and I can see how it would be great for inter-positives, however, I couldn't get nearly enough dmax out of it for my uses.
I am curious about D-23. Can you clarify if it would be used for some reasons as LC-1 (extremely low contrast inter-positives)?
As far as the Extend Plus goes, I'm finding that a dilution between 1:15 and 1:20 will probably work. It also needs some good agitation, as compared to using the HC-110 (which is consistent but really really minimal).