B&M are just as reliable as any other, it is just that B&M go for more classic style rides (lift, drop, loop) which tends to be non complex and only has a limited things can go wrong
If you saw an intamin lift, drop, loop it would possibly be about as reliable if not more reliable than a B&M. But intamin make things like launches, cable lifts, LIM's etc that have more things that can go wrong. The result is that B&M's up times look amazing until you look at the more complex B&M's like Air, it has possibly had more down time than rita. And that is the problem with roller coasters the more complex you make them the more likely they are to break down.
What I am trying to say is that B&M don't really do new designs because their name isn't really in doing 'First evers' but god ol'fashioned rides.
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