And the argument that it used to be the preserve of the upper class so it's snobby and pretentious if anyone else does it.... Er, what? How dare the middle and working classes care enough about their names to think that it matters that their children share them, eh? It's only if you're posh that your name matters, right?
Well I guess OP can see that some people will think one thing about her if she uses both names, and some another, or else nothing at all because actually, these days, double barrelled names are really, really common and not an issue at all. The question is whether she cares about the opinion of those who will be concerned about tradition and what her great grandchildren will be called, or dismisses all that as a load of confused bollocks.