Lovely. Thanks for sharing. I would have plumped for yours but I've just emerged from a vein of buying YG/RG watches, and liked the ivory dial this time.
As for the crossed 4, I'm going to hazard a guess: it's a delicate nod to the Christian tradition of its designers. It didn't appear on the font that A-L Breguet himself designed.
All of the the numerals are heavily stylised but only the 4 bears this additional touch. It has to have a significance all of its own. It's more than just a swish to do away with negative space (there isn't any to do away with anyway). That would actually be rather inelegant. No, it's more than that: it's a Crucifix. This sort of thing isn't unique. We only have to consider the Maltese Cross and VC, and the Spanish Order of Calatrava and PP.
So this would be my suggestion, and am hoping someone can speak with authority on the matter.