Hey slowtour,
I love Butterfly bars, I find having lots of hand positions to be beneficial on a long touring day. I've never been a big fan of drop bars. I guess at the end of the day handlebars are very much a personal preference type thing.
If you have MTB brakes and gearing (or a Rohloff), they simply slide onto the Butterfly bars.
The only real drawback with the Butterfly bars that some people have is having to move your hands to operate the brakes/gearing - I personally don't find this to be an issue at all.
I find the far reach is quite good for getting low into a head wind and the sides great for leverage when cranking uphill.
I'd suggest you try some out before you buy, some people love them, some people hate them...