There are some places that give you a small discount for having either. I'd imagine if you wanted to string for tournaments and weren't established already, you'd be considered more seriously if you had you MRT. But, I've seen box stores advertise that they had so-and-so number of MRT's on staff doing their stringing, and still had a terrible reputation for the product they put out. This makes me believe that like many certifications, these are mostly "bought" -- as in the box store will have a person that gives the certification test and goes pretty easy on his employees. Also, they name certified court builders, which, again, seeing some of the work certified builders have done around here, I suspect the certification must be bought (courts with dead spots from from the day they were built to clay courts with poor underground watering systems). I do belong to the USRSA, and I think if you string for others you should too. But, I will say that their stringing machine edition is pretty watered down (doesn't tell you much that you can't get by looking up the manufacturer's literature) and the RSI magazine contains a lot of advertisement etc. But, some of the readers know-how and tips are fairly good, especially for a beginner stringer to learn from.
