In lue of boredom the past few days, I've been slowly scratching off a random B&M floorless coaster, and it has gotten around to completing the circuit. This basically happened by accident, but it's gotten quite far. I'd call it a B&M concept or custom track; it's got a few elements that they probably haven't used.
http://www.nolimitsdevcenter.net/p4793
Comments are welcome.