In the Westwind you got a solid rumble just on the Mmo limit, and 0.1M over it would abruptly drop the nose about 2 or 3° - which at that speed is alarming.
The BAe 146 never got anywhere near its limits, and you could (in the sim) hammer past Mmo with almost no noticeable effects.
Haven't tried it in the 737 sim yet.