Between the Primary Arms and Romeo 5 I'd probably go with the SIG, but that's largely because I'm really impressed so far with my Romeo 4.
I think for purely a range gun the TRS-25 is hard to beat if you haven't completely ruled that out. I have two from 2012 that are still going strong, one of those is on my Buckmark and get's used at least twice a month and the other get's moved back and forth between a SIG 522, a Marlin .357, and an M&P 15 Sport. It even took a couple cylinders while on a .44 mag Anaconda, basically just enough to range it in. I also bought a "new model" TRS-25 this past March to put on my daughters M&P 15-22. I know 3 months of use isn't much to go on but it still works fine, and the red dot is actually a little cleaner than the dot on my older TRS-25's.