Sure go play the London System but...
Be prepared to play alot of boring games and get ready to fight for equality with White pieces from move 3.What do you play against the London System?
The best way to annoy a Londoner is to not play their opening. KID is a decent choice, although I’ve also considered playing a double Fianchetto setup to put those London players out of their book (always fun to see a booked up idiot confused).
However, even this sequence is enough to make a local Londoner wish he played c4 on move 2 or 3 because its hard to prove any advantage
Bottomline, I'd rather quit chess than play this opening with White pieces.
And that's why I play the French against 1.e4: to kill the fun of people like you with an opening I more likely know better (and enjoy) since I play it all time.
Does it make a good person? I hope not.
Is it a decent opening "tactic"? It is. :D
So, if a "good" player (as opposed to a weakling that don't know much about his system) make you uncomfortable in barely 10 moves, and that he gets a position he likes (close center, wing attack, easy mistakes for his opponent...), then he already have somehow the upper hand.
As I see it (this principle dictates my repertoire choice) your job as his opponent, is to make sure you make him unhappy by refusing him what he wants and get a position you like. So, work on it and London players will be a trifle in your world. :)