The trigger on the Cx4 was improved a couple of years ago. It's not amazing but it's definitely usable. I like it because it's shorter than other 16 inch rifles and balances well for shooting with one hand. It's also reliable with hollow points, which is rare for PCCs, and it has a track record of police and military use. If you use an aimpoint micro sized red dot, you can cowitness with the sights. I can shoot mine with the front sight up using the dot body as a rear sight, and reliably get hits on six inch plates at 25 yards.
For pitfalls, she might find it difficult to rack due to the heavy spring, and it has more recoil than a delayed blowback. The safety is kind of stiff and you need to use your support hand to put it back on safe. I don't know much about the ruger pcc in comparison, but I'm not a big fan of the idea of the takedown system for a defensive gun.