Louis and all-
As successful as the NYC Hudsons were, they were really just enlargements of their last class of Pacifics..
The CB&Q S4 was essentially a brand new design. I haven’t looked at the drawings for the MILW “Baltic” F6 but I would guess that the Q engines owed more to that design than the NYC. The NYC had to be designed with a tighter profile than the CB&Q engine.
The O-5 and S-4 were concurrently designed and share many details.
I wonder if the CB&Q even considered Berkshires….I think they probably felt that the Northerns filled the niche that they would have addressed and that there was no need to adopt that wheel arrangement. The O5 was a dual service machine and the roads that had both Berkshires and Northerns tended to have more passenger-service design 4-8-4s (RF&P, MP) and most roads that had good Northerns did not have Berkshires (NYC probably thought that their Mohawks filled that niche and the P&LE Berks were more experimental outside of the NYC mainstream motive power thinking).
Charlie Vlk