I shoot FP4 at box and incident meter and it is truly rare for me to be disappointed.
A couple thoughts though before you switch.
First. Just because Plus X works well at 1/2 box speed with a spot meter for you, doesn't mean every other film will too.
Second. EI 50 and placing shadows at Zone IV is like shooting at EI 25, so 1/4 of box rating, not 1/2. That means you are adding two stops of extra exposure which could easily explain your blocked up highlights in many scenes.
Third. Most films do a truly fine job but that doesn't mean you'll get along with every film. Kinda like dating, you gotta figure it out for yourself.