I rode Montu in March for the first time, and DAMN that brake! 
 
I have noticed this too. The older B&M'S (Batman: The Ride's, Kumba, Raptor, Mantis no trim, Montu no trim) give a much more intense ride than the newer B&M'S (Montu trim, Batman Knight Flight, Mantis trim, Great Bear) 
 
It's not to say that the new ones aren't as good, it just means that they are less intense. 
 
Also; Mantis and Montu were both probably from the last year of B&M intesity, and both had brakes put on. Mantis' aren't nearly as bad as Montu's.  
 
B&M saw the brakes, and heard the parks complaints, and built them less intense. 
 
Believe me, they could build some wicked stuff if a park would let them. I guarantee.