That's great news. I always swore by them.
We never fitted them as they suggested in the instructions, which I think explained cutting the middle sleeve to fit inside the outer cable. Best to cut and fit all the outer into the cable slots, run the middle sleeve from shifter or brake to the end of the last outer in 1 continuous run. This way the cable was "sealed" for the whole cable run.
The Goretex cables on my FSR are now 11 years old and it still shifts smooth, although I have to confess it has only really seen fair weather action !