The Romeo Zero is not great. It has some major draw backs.
You have to remove it from the slide to change the battery, this can affect Zero.
Changing the brightness of the dot is just plain stupid. There is a tiny button that sits just in front of the glass that you have to press. It goes up or down, then more of whichever direction it is going, then off, then back down or up depending on the previous cycle ... So you can't just lower or increase the brightness a bit easily, it will either go down or up when you press the button. Since the button is right in front of the glass, you cannot see the dot while pressing the button. Press the button, remove finger, look through site, repeat. Sometimes it isn't real obvious with one press if it is going up or down or changed at all since the button is a little hard to press to begin with. I have fairly small fingers, I'm not sure how someone with large fingers would even fit a finger into where the button is, I've heard of people needing to use pens or other things to push the button.
The screws for zeroing the dot have no feedback, there is not a click as you adjust them so it is fairly easy to over or under adjust vs what you want to do.
I was however mostly happy with mine until I started having to adjust the dot a few times at the start of some IDPA stages, and also until I had to change the battery right before a match and I'm pretty sure my Zero is off a bit now. While I'm fairly slow at IDPA I rarely am down more than Zero, maybe down One or Two on many/most stages. This last match I seemed to miss every target until I started using a little Kentucky windage on where I think Zero is off.
I'm looking at a Holosun 507, this seems to be the consensus of a number of owners of P365/Romeo Zero combinations that I know personally. Your mileage of course may vary.