SeanM wrote:How would the above theory apply to ...
...anything hung off the muzzle of any firearm?
No idea.
The people who use tuners in applications where they really need them seem to fuss endlessly to get them right. The results are worth it but the journey is tedious.
If you've ever had the experience of putting a suppressor on a rifle and then suddenly seeing groups shrink by half, you'll be a believer. Those situations, though, are random luck. I've seen suppressors cause worse accuracy, too. The same is true of large compensators, brakes, and heavy bloop tubes.
The only real-world answer to your question is: "Test. Attach the thing. Test again. Compare results."
Sorry I can't be any more helpful.
Edited to add - I can only assume that Morini did lots of testing and that the pictured comp wouldn't hurt anything. It's not in their best interest to sell parts that make their pistols less accurate.