It basically comes down to whether or not you want to spend the money. There will be a weight saving but that is about it.
If you have stiff soled mtb shoes of the xc variety (which it seems you do) then road shoes will just be lighter. The fact your foot is in contact with a smaller pedal should make little difference if the shoe is suitably rigid.
I went down the roadie route but then I’m doing quite a lot of racing.
But I also use my cx for long and mixed rides. I’ve noticed no issues doing 100-150mile in mtb shoes (shimano XC51N) and XT pedals. And the only real difference in my road setup (R170 and 105 pedals) is the weight. My road shoes save weight by having ventilating mesh all over them so I normally end up with oversocks anyway until June.