I don't have any personal experience with them, having never had access to one at a gym I regularly worked or lifted at. The only time I ever tried one was winter 2016 as a guest at a gym in Phoenix, when I still couldn't get my hands in place for low bar squats after my labrum tear, and it didn't help at all. So take this for what it is, and maybe people who have used it will chime in.
Generally it's better to try to do the low bar squat, especially as a novice and early intermediate for whom squat variations other than low bar are almost always unnecessary complexity and less effective than just low bar squatting. People who can't low bar squat can usually get themselves to where they can, with focused stretching. It requires a period of discomfort but usually they get there.
If, even after doing the low bar stretch, and hanging, and maybe dislocations - consistently and enough to actually make a difference - you still can't low bar squat, or can't do so without inflicting yourself with shoulder pain that effects your other lifts and activities in life, then you just accept that, and maybe try again at some future point.
I don't know how bad your shoulder pain is. Some discomfort is worth it, if it doesn't rise to the level that it effects your other lifts or activities. If it does, OK. I also don't know how much you've tried to improve your range of motion beyond a couple sets of the Horn low bar stretch. It has acute effects, yes, but it's the chronic effects of doing it a bunch, several times per week or more, that add up over time to get you to where you can low bar squat. Based on your post, I'm not convinced you did that.
Usually we just use high bar for people like this. But if the buffalo bar allows you to use low bar mechanics, then yes, I'd think it would be a preferred option. Since I don't really have experience with it though, I don't know - is that the case? My only concern is that it looks like that kind of bar wouldn't sit stably and still in place while lifting. It looks like it'd be unstable. But since I haven't really used it, I don't know - and I know lots of powerlifters use it, so maybe not. Someone who's used it may have better insight.