Screen tearing is the big pain of X11 in my experience. Most things work fine, but watching videos or playing games is a terrible experience when dealing with constant screen tears.

I tried a bunch of different configs and was able to minimize them significantly, but they were still there.

What you gain is that programs render at the native resolution of both displays. In terms of appearance, it looks noticeably clearer, since no downsampling or upsampling necessary. But the nicest thing is that it just works — I don’t need to configure any settings to prevent windows from being displayed unreadably small or gigantically large.