The one single thing that bothers me most about interaural crosstalk is the cancellation dip that occurs at the ears for the phantom center. For a typical 60 degree triangle this first dip occurs around 2 kHz, which is about as bad a place for a dip that you could ask for, taking the crispness and articulation out of center panned vocals and instruments.
If you push the speakers closer together you can push the first cancelation frequency up higher. That's good, but then the stereo effect is also minimized. If you push the speakers wider apart, that will push the first cancel down below 1 kHz, which I found is also good, as the upper frequencies will not get comb filtered as severely because of improved head shadowing.
Lately I've been listening with about a 110 degree triangle and find this very satisfying in terms of giving a crisp, clear sounding center image. I get the impression that for me, late reflections can fill in below 1 kHz with less perceptible loss in clarity and presence than up at 2 kHz.
I've also tried various crosstalk reduction methods, including a 3 speaker array that I dreamed up. They work, but seem to always come with a side effect or two. I haven't tried BACCH, but I tried a competitor product that sounded excellent. It didn't overly widen the soundstage while also producing an excellent tone and clarity for the phantom center. My main issue with it was latency from the processing. The other was that it needed the speakers to be closer together, and my room layout works better when the speakers are spaced wide apart, which to my ears sounds about as good overall.
The best I've heard is from using a physical barrier. It's exceptionally clean and pure sounding, creating . I also think the arrangement ends up improving room acoustics considerably because it ends up dividing the whole room's early reflections into more exclusively left speaker reflections on the left side of the room, and right speaker reflections on the right side of the room.