Are you sure you arent confusing B-Roll with the fact that when it came out they called their videos "B-Roll Footage" which is basically video speak for "stock video footage" ?
RCDB doesnt use that anywhere for the element breakdown. Nor have I seen any information calling it a "B-Roll". That doesnt even make sense. Not that every other crazy name does but I think you have mistaken B-Roll footage for the name of the element.
Either way, I would suggest either using a straight element with rotation on it, followed by a multizone element for the loop. The second way would be to use only multizone but you would have to be comfortable working with high lateral and negative vertical G's.
Never use straight geometry if you dont have to tho. I would say have a .8 lateral bump like ajclarke sed. And have vertical gs transition to about -.8 until upside down. Like your making half a barrel roll.
Still can't get it when using Multi-zones....I can make it functional with straights but it's nothing like the real ride because the real one begins to curve at the same time it's rolling; which bring me back to using multi-zones. If anyone who's more experienced that would like to collaborate on an X-Flight Recreation I'd be more than happy to.
I'm building X-Flight in nolimtis, I first started out using newton. First drop looked good, Zero-g roll was great, Immelman looked awesome, 2nd zero- roll was fine. Then came the inline twist.... I could not figure out how to get the shaping right. Im now building it by hand haha