Good choices, Nicolas. The Montegrappa is the largest and heaviest of the four — feels substantial and has a wonderful nib. It is also the most expensive of the four.
My favourite was the Cartier Pasha. I divested of them once I found I rarely wrote letters and now only own a MB. Mainly as an accessory for my office desk.
I have the Montegrappa Extra 1930 tortoise shell in the rollerball. Thinking that I should add the fountain pen. Currently inked is the Montegrappa Miya.