I think I would find it more disconcerting if I was going by only the family last name, rather than both. Since I've added a name rather than changed a name, I don't mind not having bothered with the legal change - I still think I might someday, but it's taken a while to even be interested in it.

I actually find it more disconcerting when my grandparents send me a check for my birthday addressed only to myfirstname husbands-lastname, and then I endorse it with the signature of myfirstname bothlastnames. But one reason I don't want to change my last name officially / legally is that signing my name differently is just...wrong somehow.