I bought a full sized P320 just out of curiosity a while ago and got a good deal being Certified Pre Owned. A novelty (to me) is being able to swap out grip frames easily. So I also experimented with medium vs. large grip frame in both the full sized and compact frame sizes.
The novelty wears off. Once you find what grip size works, the tendency is to just leave it in. I suppose I could treat the extra grip frames as spares in case the originals are damaged. I find the medium very comfortable and the large grip frame is odd in that instead of just increasing the overall circumference of the grip and keeping everything proportional, there is a ridge on the back that forces you to slide one's hand more towards the counter-clockwise direction. I bought compact magazines to go with the compact grip frame, haven't had the time or the holsters to try carry them out and about. I live it with a full size frame, in medium size. One thing I do appreciate about the grip shape is that it is oval in cross section. A lot of polymer pistols have side panels that are completely flat, so you are kind of gripping a rectangle. An oval lets the palm of my off hand make direct contact with the grip and apply more pressure to the grip rather than onto the fingertips of my strong hand.
My full size shoots well. It's a little bigger than it needs to be, as the P320 was made to have the same form factor as the Sig P250 which is hammer-fired. There really wasn't a need to have the slide be so tall on a striker-fired gun since you don't have a pivoting hammer to accommodate. But the tall height of the pistol is actually very comfortable for me to shoot with. The trigger is nice, still gives the feeling of being a crisp break although if you look at it, mine does travel a little bit right before it breaks but it hides it well. So not quite like a 1911. But still a good trigger. I'd imagine with all the noise (in a good way) about PPQ triggers the PPQ might have have a "nicer" one - I've never shot one. While I am curious about PPQ triggers, I'm also aware that a lot of people make a big deal about triggers when a little practice can trump a lot of trigger characteristics. Trigger reset strength on my pre-owned specimen is less aggressive than what I am used to, but it could be on my example. Grip frames are around $25-30. Again, novelty, I have spares if I ever damage my grip frame after using it to... do something that breaks it (like what? I don't know). And now I'm familiar with a current military sidearm. Except I don't have the official M17 with a thumb safety. Worth $500-some dollars? Not to me, but I got mine for about $380 after the FFL transfer fee. It's simple and reliable.
