I had to decide between the NRS Mission drysuit and the Kokatat GMER this spring and after reading up on the two, I went with the Mission and the eVent fabric. Main differences in my reseach were 1. breathability, 2. price, 3. booties (fabric vs. latex), and 4. longevity. The eVent fabric and the Gore-tex fabric are actually very similar in construction materials and process (as opposed to very different than other products sold by both gear companies and others that say that they are "breathable"), but the eVent has larger pore spaces on a microscopic level, leading to the claims that it breathes better than the Gore-tex.
When I spend that much $$, price really was a secondary consideration - I wanted a product that I felt I was going to be happy with long term - probably the rest of my boating career. $100-$200 isn't a major deal amortized over the life of the product. I read A LOT about the benefits of the fabric booties vs. the latex, as well as personal testimonials, and came to the conclusion that the latex ones will likely hold up better in the long run if cared for. The breathability for your feet really isn't an issue anyway, especially if you are wearing wet neoprene over them. The latex is more durable with gravel and sand particles abraiding them.
The breathability of the eVent fabric was definitely a selling point (living here in AZ where it can be hot in January) and comfort is important to me. Again, I read a lot about this fabric not only as it relates to drysuits, but also other outdoor rain gear and it really is getting rave reviews for outerwear, it's just not really hit mainstream yet due to the marketing giant that is W.L. Gore Inc. Just as dry as Goretex and better breathing. OK, sounds good. I wore this drysuit in cold weather (snow falling) on the Chama at the start of May and was COLD it breathes so well (was really expecting it to be toasty inside the suit). Had to layer up a little more underneath the next day to be comfortable. Since it breathes so well, I really got the evaporative cooling thing going right through the suit when splashed with water. I think this would be an excellent suit for a moderately warm day with only a quickdry t-shirt on underneath. No overheating to worry about or buildup of sweat.
Lastly is the longevity. This was a tough decision. Kokatat's backing of its Gore-tex products is legendary. I read stories about it all the time. A little delamination and the owner gets a new suit shipped to them. Wow. That was honestly the toughest part of the decision, so I called NRS and queried them on it. I was regaled with their "Rock Solid Guarantee" and I honestly believe them. They make good, no, GREAT products in my mind, but this is still new territory for them with this fabric. The question is, will the eVent manufacturers back up their product like Gore does theirs, if and when the fabric has problems. That's
the question no one yet knows the answer to.
a guinea pig here. Fully admit it. One of a few that wanted the best and went with the new kid on the block instead of the old tried and true. Yeah, I saved a little moola at the same time, but that matters not if the product doesn't hold up for a long time. After reading about eVent and the differences (and improvements) versus Goretex, I was ready to give it a try, because it really could be a great product long term. It's seemingly durable and very quiet, not to mention quite comfortable.
As for the cheaper suits (like those that are $300 to $400 cheaper than the GMER) I would say that in those cases you are buying a suit that will be a place holder until you desire or can afford a better one. eVent may have gone the way of the dodo by then, becoming another in a long line of coulda-been contenders, and Goretex may still be King of the Kill, but there is also a chance that someday, someone will come along and knock that king off, and I laid down a bet (foolish though it may sound, and basing it on more on my research than a gut feeling) that eVent has the best chance to do so since I can remember.
One other thing. I wouldn't fault a single person for buying a GMER and would never try to sway anyone from going that direction. That product is totally proven and solid.
A little info (older, though it may be) on the Goretex vs. eVent
Get Outdoors - eVent versus Goretex Pro Shell: The Battle Lines Are Drawn - Getoutdoors.com Outdoor Blog
Choosing the right waterproof jacker and clothing for you - Climbers Shop Gear Guide