IMO, it's a big risk to depend on Swihart to catch 40% of the games, and I say that as a Swihart fan. He really hasn't had enough playing time in the majors recently to know what to expect from him. He could be pretty good, but then again, he could be pretty bad. Not only defensively, but offensively as well.
Out of our 3 catchers, Vazquez is the one I'd least want to part with. As you said, I'd rather go light on the pen.