Well, I think it would sell for quite a bit more than your £100 Dave - the nib alone would be more than that to buy, even without the name. I would certainly accept one as a gift, which I'd hang on to for my grandchildren. Like or or loathe it, value for money or not, Montblanc have manoeuvred themselves into a position of aspiration in the market place, and a pen like that would be an investment rather than a reckless purchase. The same is not true of all Montblancs however, but some, and I suspect that this one will turn out to be one of them, change hands for many times their initial cost years after they were first bought.
At 71grams I notice it's very heavy, but there again it's only ever going to be used by most for signing letters and sitting there looking good on the desk.