I believe that belts are helpful only to keep students motivated. As we all know, certain schools/teachers will guarantee a belt as long as you complete the training. To this end, belts do not signify anything. If you are training to be able to defend yourself then you should be more concerned...
As a long time martial artist, I was always skeptical of many of the claims that were made about power and techniques. Does anyone use technology to validate his or her training? Would anyone buy a device to attach to a bag that measures impacts?