I don’t know about being over- or under-rated but my opinion is that the SIG P320 is an excellent pistol. Of this genus, I have an M17, a full size 320 “clone” of the M17 I put together, and a P365. I also have Glocks 17, 20 and 21, all of the Gen 5 variety.
High bore axis? Non issue, especially in 9mm. The 9 is such a pipsqueak in any of these pistols that it scarcely bears mention, much less debate. My 13 year old daughter loves the P320 and finds it easier to shoot fast than the .22 P322, probably due to cadence. She’s no pro but she shoots a lot of handguns in the .22 to .45 range and she loves the SIG for its controllability and light recoil.
Trigger? It’s mushy, but like Hungry Jack mashed potato flakes. There’s smooooooth takeup followed by progressive increasing resistance followed by BANG and a little overtravel. For a striker fired pistol, it’s excellent. Better than a stock Glock gen5? Hands down better. Better than a Glock performance trigger? Yes. I put one in my G17 and there’s no comparison. The smoothness and predictability of the SIG trigger is worlds better than the stock Glock triggers. Do I hate Glocks? No, I love them. I already have 4000 rounds through my Glock 20 and shoot it routinely at 50 yards. It’s the gun I’d probably carry into Hell if I had to.
Is the SIG trigger better, though? Yeah. Yeah. It really is.
Accuracy. Not a lot of practical difference here. All of my service pistols group 1.5” to 3.5” offhand at 20 yards depending on load, sights and how my arthritis is doing that day. I can’t imagine the Dagger being any different.
SIGs generate a lot of love/hate issues. Glocks too. Like anything, the outliers need to be excluded as emotion clouds judgement (though emotional people tend to hate to hear that and reject the assertion. How dare you). Try the SIG. if you don’t like it, don’t buy it. I have NO experience with the PSA Dagger so I can’t comment directly. If you like the Dagger, buy it and shoot it. No one will be there at the cash register, and you’ll be the only one that matters at the range when you shoot it. The good news is that there is no wrong answer; get the gun you WANT and shoot the daylights out of it.