Open Headphones, Yay or Nay?

So I'm looking into getting a new headset and can't decide what would be better for me, the Audio Technica AD700x or M50x. The only reason I'm considering not getting 700x is because I use headphones in places like libraries and on public transport a lot. The sound may annoy people in the library and the sound could ruined by the loud sounds the bus makes. Both of these could be prevented by getting the closed set but I've heard that open sets beat the crap out of closed for gaming, of which I do a lot,  so I'm stuck. Would the sound bleed, in and out, be small enough on the 700x's for my sort of use? 

TL;DR : Open or closed headset for music in semi-loud / public places where you should be quiet and lots of gaming at home  

There are closed back headphones that can give adequate soundstage, but M50X isn't one of them. It's a very forward sounding cans, in that it has music-is-playing-inside-your-head-sensation. I would recommend something like:

Brainwavz HM5 which is a licensed FA-003 by Fischer Audio.

Or, try the updated version of that by Fischer's themselves, FA-003Ti which has the same drivers but with titanium coating and options for wooden versions of cups which further the flavor of soundstage.

[FA-003Ti with Sapele Wood cups for much added bass.]

 

Both come with accessories relevant for travel and portability. Oh, and they're both neutral so you get to enjoy multifaceted genres.