it depends what you want to do with your device and what your usage habits are... for example if you are mostly going to be connected to wifi, and using your phone as a email and social network machine, with occasional gaming and music streaming on network then id say go X2, if your going to be downloading large files from email or streaming a lot of HD Video then go with the breakout. 4g is nice and its fast but with a breakout its a tough call.
To put it in (my beloved) non-phone terms think of the X2 as a V-8 Mustang in the City and think of the Breakout as a bone stock Cobalt on the Freeway... one is clearly going faster, but that doesn't mean its the faster car.