Inkdot, I can understand your concern. If the request were for information about serial numbers of contemporary Montblanc models, then I would be worried about putting the information in the public domain for people to use to produce pirate copies (or whatever)
But in the case of the vintage Auroras, we are talking about a pen produced in massive numbers in (mostly) the 1950s, where the serial numbers are essentially sequential, and where it is next to impossible to produce fakes. In this case, I don't see any harm in providing serial numbers (I have done so on the other thread), as they can only really be used for the purpose to which Praxim wants to put them, namely helping people to put a production date on specific models (either their own or something they are thinking of buying).
Bo Bo, I have two vintage Aurora 88s, as well as a couple of cartridge versions (using Parker cartridges/converters). The nibs are wonderful; very bouncy (I'd call them semi-flex, but am careful with the F-word). Having said that, you do have to be careful with the piston-fillers (neither of the two that I bought were working - I jerry-rigged a solution for one of them (would horrify a purist, but it writes now!) and one remains in need of repair).