LIke all of you, I started in the pre-GoreTex days, and I fully agree that rain wins every time, if you stay out in it long enough, regardless of your rain gear. I forgot to say, in my Pertex post just above, that the synthetic clothing dried very quickly - probably in 10 minutes or less in the car. In the field, even when I'm fairly wet, I'll be dry in half an hour after sheltering, regardless of the outside temperature. So, the real breakthrough in rain gear might not be the shell - it may be the ability to reliably get dry after you stop.
Since I already have the Pertex and GT garments, I probably won't replace them with coated nylon (unless a rash moment of ounce-paring sets in, and I have no adult supervision available.) I'm probably going to focus also on the suitability of the garments as wind garments, or a way to add a little warmth in a cold-weather hike - in which case, breathability becomes an asset (you don't need the WP, just the B.) I had that happen a couple of months ago, the day after a big rain, when the temps stayed in the 40s and 50s and there was one of those fog/mist/humidity days in the woods. The Pertex worked great for that: the light vest, long johns and shorts I was wearing stayed dry and I stayed just warm enough. Not sure that would have happened with coated silnylon - or 2 or 3 layer GoreTex, for that matter.
If there is a circle in hell for backpackers, it will be raining and our only choices will be WPB fabrics, I suppose.