I'm just wondering if there was a reason why they chose a B&M coaster of all things instead of something else then I think it might be linked in with Nemesis' retrack.
With these rumours that Merlin have a deal with Mack to have two attractions installed with one being Project Exodus and the other either a overhauled Duel ride system or maybe for Project Horizon which making two rides at the same time can keep costs down as in a two for the price of one thing going, maybe the only reason why Mandrill Mayham is an B&M is that Merlin needed to find a way of keeping costs down for Nemesis' retrack?
Think about, if Nemesis was the only B&M coaster that Merlin were focusing on then it might be expensive for just one yet of installing another B&M at the same time might be down to keep costs on both rides down, maybe that is the only reason Mandrill Mayham was built anyway as in just to fill in the deal as I agree it seems overbuilt for Chessie and might have been better instead for Project Exodus but then again whenever have Merlin made smart choices?
One thing this new ride has in it's favour is that it is the nicest looking Merlin coaster they've ever built and visually should be heads and shoulders above other coasters they've built from Thirteen, Smiler, Swarm...actually a lot TBH.