The grip length is more likely to print than the barrel length. The heavier gun will put a greater load on your waist. If you're a bit pear-shaped, that matters. A thinner slide/gun is less likely to print (and of course, holster choice is a huge consideration). A hand(s) filling gun, and heavier gun (within reason) is more controllable (I don't think anyone competing in USPSA Open class shoots a small, light pistol, capacity aside).
Your lifestyle and "dress code" might dictate what is concealable for the clothes you have to wear daily.
And those narrower slides will pretty much dictate the smaller, skinnier red dots, e.g., the Shield RMS and the Holosun 407K (I believe that's the thin model) use the same slide cut footprint (at least my P365 cut did). As noted, the RMRcc cut is unique.
And to go off the rails slightly, if you haven't tried it, the P365 variations with the factory optic cut might be worth considering. Most who've tried them are pretty satisfied with them.