If the strings are too light, the guitar won't speak as well--it loses volume and the tone deteriorates---but you probably won't have extraneous noises become a problem until the strings are too rubbery to get much sound out of, anyway--I generally use the heaviest strings and instrument will take because it sounds so much better---if you are having a problem, though, you have to do what you have to do--

It might be time to shop for a new instrument--one with more comfortable action--a shorter neck might help, also, because the tension on the strings will be less--classical guitars are gentler on the fingers as well, but it also might be time to re-evaluate your fingering techniques and iron out bad habits that might be causing you discomfort--