There's a fundamental issue with Gore-Tex that depends on the climate on the inside as well as the climate on the outside. If you've just hauled your machine out of a boggy hole and are steaming inside, then hopefully the vapour molecules (smaller than water) will cross the Gore-tex layer and condense on the inside of your jacket and not come back to you - but if anything affects the layer size/composition/continuity in any way; tears, salts, cleaning fluids, etc then the water will wick back into the inside and if the outside is soaked then that will wick through as well.
An outdoors activity instructor I knew reckoned he would buy decent Gore-Tex jackets with a couple of years minimum guarantee and would always find they would leak within the guarantee period - they expect garments to be used on an intermittent basis and certainly not as intensively as he used them. I have found fabric walking boots particularly prone to failure in a very short period.
I think Gore-Tex is fine initially but it takes very little to compromise it. Once compromised there's not much, if anything, that'll fix it. Keeping the water away then is the only option.
