I've considered it, in the abstract/hypothetical; we would need a substantial fencing upgrade, but then, we do anyway. Which probably won't happen unless the money meteor strikes, or I develop a lot more vim and vigor and enthusiasm for cutting and sinking a whole lot of red cedar and osage orange
fence posts.
What I found out is that reproduction in bison is an issue unless your herd size is big
enough to keep at least one bull. Who will be even bigger and more dangerous than the cows, and that much harder to
fence.
The thing is, with cattle, I gather you can just keep a couple of cows, and get the vet out with a syringe of purchased semen when you want babies. (I know, nothing is that simple in real life...) With buffalo, it's impractical-to-impossible in most locations. For one thing, standard cattle chutes apparently aren't big/strong enough; you need heavier buffalo-engineered handling equipment to get them veterinaried in any way. Expensive, probably not practical for too small of a herd.
And then there's the problem that buffalo semen for artificial impregnation is not a regular item of commerce like bull semen is. I'm not saying you can't find it by special arrangement, but you can't just order it up readily. Or so my internet searches told me.
So, if you've got the
land for a complete herd, maybe? But if you're dreaming, like I was, of just having a couple of happy bison cows ranging on the back forty, with fuzzy calves in tow that you butcher when they get just the right amount of big enough -- that's not as easy as it sounds.