This is a good question, and one I wish I had known to ask.
I have Billie bars on my Sam, through a single bolt Nitto Tallux stem.
They have only moved once, when I dropped into a stream crossing that was much steeper than I expected.
(This sounds like it looked cooler than it did. It was no
Man From Snowy River.)
That being said, the leverage of such long bars is undeniable, and I never feel I can torque on them as much as I other wise would like to.
I bunny-hop a little gingerly... Pull-up over curbs mindfully.
If I were to ever make a bar change of any kind, I would switch my stem to a face plater.
k.