I have not done a lot of B/W printing lately. I tried some alternative process experiments and fell head over heals into Kallitypes and printing on Japanese papers I make myself. Darkroom mess compounded exponentially!
I bought a P600 for making digital negatives about a year ago. I like it and have had no trouble with it. One advantage is it has a 60ml capacity vs 25 in the P400.
You already know about IJM carts
Best
Kelly