I load a fair amount of 300 blackout. My only supersonic load is with H110 and 115gr Lehigh controlled chaos running somewhere around 2,200' out of a 10.5" barrel. My go to powder for subs has always been 1680 for a variety of bullets from 190-225gr. I load my hunting subs to 1,000 fps and all my plinking subs around 900'. 1680 is impossible to find lately so I'm slowly switching out to CFE BLK with good results so far and I may just stick with it. I shoot suppressed 100% of the time so the subs make a lot of sense, especially considering that's kind of the point of the cartridge.
As far as hunting goes, the past few years my wife and I have both used our 300 blackouts for shooting bears over bait typically in the 10-75yard range. Something like 11 or 12 bears (a few were over 6.5') with the blackout, half being with the 115gr controlled chaos(supers) and the other half using 190gr Maker REX with a muzzle velocity right at 1,000' (subs). None of the bears have made it more than ~30 yards regardless of using subs or supers and the subs exit more often than the supers do. It's to the point I don't have a preference between the subs and supers for hunting because they both work equally well. They work in different ways, but the desired outcome is the same. That said, I think the bullet choice is what makes the 300 a viable hunting choice or not and obviously shot placement. If you use crap bullets and/or are a poor shot, then expect subpar results on game and don't blame it on the headstamp. I shoot a fair amount of lynx, fox and coyotes with it too when I don't feel like carrying a longer rifle.
For spot and stalk bears I'd opt for something with a bit more power for increased shot distance and ability to take shots at less than ideal angles. Over bait where we have more control over the distance and how the bear presents a shot angle the little 300 works just fine. If you cant kill an animal with a subsonic round then I'd say you probably suck at hunting, shooting or both.
This is my experience based opinion and I suppose it's worth what you just paid for it.