I don't see the issue with installing master sockets yourself, as long as its a professional install. I have had two engineers out back when I had a line fault at the pole, and none of them commented on the master socket install, which by the way was moved to a completely different room from the original entry point. So as long as you know what you are doing you will be fine.
Also I am excitedly awaiting for the NTE5C and new (mk4) Filter to become on sale somewhere, I really want to see if there is much improvement in line stats.