Speaking from personal experience, I think all this will do is change your speech patterns and modulate your accent ever so slightly.
You likely read/write English better than a native English speaker already. Some of the language/grammar I've encountered from my English colleagues in both formal and informal written communication is absolutely terrible, and I attribute that to them "learning" English by way of speaking and "incorrect" colloquial usage before perfunctorily running through their English lessons at school.