I have the butterfly bars on a MTB conversion to rigid trekker.

The bars have some low to high curve, which you can emphasis with a tilt. The open part is toward the saddle, with trigger shifters and brakes mounted there, and foam grips. The side and front of the bars have nothing mounted, it's all handspace, Brooks leather. I have my hands out on the front when I'm stretching / low, on the sides like I'm riding hoods, close in on the grips when control is important. I also have carbon short risers coming up from the inside bar ends, they make for comfortable palm rest for upright chillin. I took me a while to get used to all this, but now I would not go any other way on this type bike. On my roadie tour bikes, drops; always.

One thing that isn't obvious when you look at these online is they're damn heavy for handlebars, massive.