I have been playing on a Monette Prana B6S1 for half a year ( on my trumpet). It’s similar to the Bach 3C. As you say, the mpc fight against me if I blow to hard. Can’t say if it’s the same with a Bach 3C. When playing with minimal press, straight forward, it is easy to play in tune.
I have been playing on the B2S3 for many years. It’s bigger and gives a nice darker tone. I thought it would be easier the reach higher range with the smaller mpc, but in my case there is no difference.
I also have a Monette 6L, which is similar to Bach 3E. This piece is too small for me, but that might be because I have get used to the bigger ones.
When I run on the cornet I use a Monette B2S3, and that is perfect for me.
On the flugel I use a Monette F6 and that mpc give me alla I want.