I think this is a decent evolution of the naval system.
For those concerned about slow vs fast, I wonder if reducing the ops points from 2 to 1 would be a solution to model those slower ships?
EDIT: the above is probably too drastic, but I'll leave it for discussion.
Also, considering the discussion about how ships don't "upgrade" throughout the war. Consider the following:
-some ships were fitted with additional AA
-improved fire control procedures
-improved search and rescue
-improved ability to recover battle damage
-improved ordnance (especially torpedoes, more of a PTO issue of course)
-improved sailing skills--even just simple navigation improved throughout the war as a result of more accurate weather forcasting
-improved sailors training--especially in terms of gunnery
According to the US Navy, here is an example of one such ship's treatment after Pearl Harbor where "She spent the rest of the year
receiving permanent repairs and improvements, including a greatly enhanced anti-aircraft gun battery."
https://www.history.navy.mil/our-collec ... bb-36.html
So I think it's not whether these ships upgrade but rather which stats should improve.
As far as BBs, I'd buy into improved surface and AA. Not so much in the ASW area...at least for BBs (that's a terrible role for them). For defense...gotta think on that. Assuming that factor represents more than just armor, I suppose it still works.