Including safety improvements is obviously a Good Thing, and in this particular case, I don't see any downside to Hollis using different threads or fittings to keep divers from putting the counterlungs on backwards. The real issue, though, is that it's just one more example of a diver not using the safety equipment provided--there's no way that she could have built that unit the way she did had she just used the supplied checklists. The surprising thing to me is that she was a recent student--you usually read about divers taking a little more time to become that complacent.