I had some boots with a Sympatex membrane that performed seemingly as well as some Gore-Tex. Personally I think that the design and construction of the garment or footwear is far more important than the particular brand of waterproof-breathable membrane used and am highly skeptical of any test data provided by the makers. I think it is worth noting, however, that the military chooses to use a lot of Gore-Tex over the alternatives.
I've had numerous garments with Gore-Tex, eVENT and various proprietary membranes and they all perform well only if the maker that is using the material properly welds or tapes all seams and uses waterproof zippers. I've been soaked wearing some Gore-Tex boots and kept dry in others and the same goes for shells. I have a strong preference for 3 layer construction in garments for durability and for ventilation features such as pit zips as none of the membranes in my experience permit enough moisture vapor transfer on their own so the fact that Sympatex or eVENT transfers more moisture vapor than Gore-Tex carries less weight than other factors in my decision making.
Regarding durability and moisture transfer, be sure to consider your entire layering system. For example, wearing a rough & rigid cotton canvas shirt under any 3 layer shell is going to abrade the inner layer more and not transfer as much moisture than something softer that transports moisture better like a merino or Polartec Powder Dry top.
I'm a big fan of micro-porous membranes but often wear alternatives including old tech waxed cotton and when it is warm I am more apt to wear a silnylon poncho than I am a shell because it ventilates so much better. When I'm ankle deep in mud or water I'm more apt to wear Muck boots than I am leather & Gore-Tex boots.
