Thanks for all the suggestions, I always thought about checking out In Harm's Way (and Duty and Honour, for that matter), and I definitely knew about GURPS Scarlet Pimpernel, but I must say that I think those couldn't convey the exact emulation one expects from a French Revolution game.
When someone goes for a swashbuckling game, it is expected to go for different shades of fencing schools and such, and that it should matter in game.
By the same logic, a military history RPG should go for gritty and tactical, whereas a French Revolution game, imho, should go for gritty, political and unpredictable.
And don't get me started on Scarlet Pimpernel turning the revolutionaries in villains.