IMO it is definitely ok to change your filter media...any and all of it...as need be because the bacteria we rely on are not solely limited to living there and do, in fact, take up residence in your tank as well; generally on things such as the substrate, decorations, plants, and even the glass. Basically anywhere water, and hence, ammonia and/or nitrite pass by them. I do agree that you don't need to chance the biofilter media in a filter very often but it is definitely a good idea to rinse it out in order to remove any detritus that may have become trapped because it not only adds to the bioload, but can also cause problems for the bacteria it may be covering.
Also IMHO, the best thing to do is to stick to rinsing the media in water from the tank as you are performing water changes. The primary reason for this is because the bacteria is already acclimated to the exact water chemistry and like our fish, they can be damaged from experiencing a sudden change in chemistry, including temperature I believe...so, in reality, unless your tap water is both the same as your tank water at any given time and does not contain chlorine, it's better to rinse with old tank water.
JMOs,
TG