I can tell you, Gerard is an amazing host for Barcelona!! He takes care of you, before and during your trip with a lot of advices. His flat is just perfect, very clean and mostly it is in a quiet area. You must be sure you will sleep very well, and one other advantage is the localisation, 2min to the underground and 10 min to go to catalunya.
So I just can motivate you to choose Gerard as host. :)