I think you're referring to how they use the variable frequency drive- it slows you down at the top of the lift so you can hear "Don't... go in... the shed..." then speeds back up to send the train over the lift. I think it's that action of speeding up so quickly that makes you feel like you are being flung over the top.
EDIT: To answer the question, yes. B&M uses ABB DC motors on their lifts, coupled with a DC Drive. You can really notice it traveling up Banshee's lift, if the previous train has not cleared the block yet, the lift will slow down until the train is safely in the brakes.