That Gamestop guy obviously didn't have a clue because it's definitely optimized on the Pro. There are three separate graphics detail/framerate modes you can choose from (though only a higher res TV will really benefit from 2 of them), and the High Frame Rate mode has the game running the best I've ever seen in this series (this coming from someone who found certain situations nearly unplayable last year due to framerate). I feel like the load times are just a bit better than they were last year too (when I only had a regular PS4).
The feature set is the same of course, so answering whether it's worth it is a hard one and comes down to personal taste. I had more reasons than just this game so it made the decision easier for me (my original was malfunctioning such that I would have had to send it for repairs, plus I needed more HDD space)
This game does see definite performance improvement on the Pro - that I can say for certain.