IMHO both designations are beneficial and useful only if you intend to start a management company or want to work for a management company that "appreciates" the designations, generally an AMO firm, and the efforts involved to accomplish receiving them. The designations are great as a means of networking with others in the field as well and they are useful to stay on top of the latest real estate trends. As we all know, these constantly change.
CPM is a residential designation and CCIM is a commercial designation both affiliated with the National Assn of Realtors. I have had the first since 1989 and the second since 1999. in addition to the thousands spent on course fees, both require continuing annual membership fees of $600 per year each. They are considered the "degree" in real estate since there really is no degree available in real estate. I understand that NYU and other colleges now offer similar certificate programs however.
I worked for one employer that encouraged and paid for my education. My second employer could care less about designations. He was the type of guy who could analyze a property in three equations in his head, very similar to the 50% rule, and make an instant decision if he wanted a property or not.
When I was laid off what saved my butt was the foresight I had 24 years ago to invest in income producing property that today supports me. If I applied for a PM job today I am sure the designations and experience would better my chances of being hired for a position so yes there is an advantage on one hand. On the other hand, salaries have been cut in half with the state of the economy and the laws of supply/demand.