I probably could do everything I need to do with the 223. This year at deer camp I brought both my 223 and my 6.5cm but ended up hunting with my 223. I had intended to hunt with the 6.5 but I had not shot it in quite awhile other than a quick zero check (which was off about an inch high and right but fine for what I was doing). The 223 on the other hand I had been shooting the crap out of all summer and fall and was dead nuts on. It worked great just as I expected it to.
So why am I going to hunt with a 6cm or 22cm this year? Im at about 700 ft elevation and hunt in pretty cold weather so DA can get pretty low. My 22 inch 223 is perfectly fine but the range gets a bit tight with a 16 or 18 inch barrel. Still fine for most likely shots but there can be shot opportunities that I would be comfortable with that are getting below 2000 fps and pushing close to 1800 fps. Those same shots are comfortably above 2000 fps out of either of the fast CMs and 16.5 inch barrels.
I would not feel particularly limited hunting with the 223 of whatever barrel length. But the 22 or 6cm removes any potential limitation. A three gun combo of 223, 6cm, and 6.5 PRC would cover anything I may potentially ever want to do (the range where the 6.5prc is fine and the 6cm is beyond my current abilities anyway) and there is enough overlap that any gun could sub in for any other without really causing a big issue.
If I needed a 1 gun solution for everything it would be a 223, a 223 + a 6cm 2 gun solution I think is better for me though.