Vapor barrier liners (VBLs) were used in army boots in Korea.
After this, a SoCal aerospace engineer named Jack Stephenson invented a neat cylindrical-shape backpacking tent. Then he expanded to sleeping bags and clothing. His company, Warmlite, gained notoriety for a 70s catalog featuring himself, his wife, and male and female friends exploring the Sierras au naturale. He later moved to New Hampshire, where his son runs the company today.
Stephenson was the foremost promoter of VBLs for outdoor products. His sleeping bags were highly regarded, premium-tier, for serious outdoor adventurers.
Nonetheless, VBLs for sleeping bags became controversial. Many users complained of discomfort from perspiration condensation. Stephenson lambasted them for being too stupid to vent their bags properly. VBLs didn't become an industry standard in premier-tier bags, but were and are offered as an option by a number of companies, because some people love them, and have no problems tweaking the venting, or don't mind being a little damp.
For active, highly aerobic pursuits, VBLs retain heat, and are popular for foot-covering for cycling, but they do lead to wetness.
You can get expensive VBLs or cheap ones. Produce bag foot covers, dishwashing gloves under insulative gloves, coated nylon rain jackets and pants... Closed-cell neoprene is a very effective VBL, and insulative. Gore-Tex, eVent and other "breathable" laminates actually have significant VBL effects, which is why every laminated jacket for cycling worth buying has venting at the wrists, pits, front, and sometimes back: without these, vapor gets trapped and condenses.
If I were looking at experimentally testing expedition mittens, and I liked RBH's VBL concept, I would call them and ask for a 30-day no-cost, or low-cost trial. The worst they could say is, "You want them for biking? They're not designed for that. Sorry." Or they might say, "That's interesting. Okay, we'll let you beta-test them for us."
If they weren't willing to let me try them out, I'd go with AltiMitts from REI. Doesn't matter that they aren't designed for biking. If, without a VBL, the insulation gets damp and I don't like donning them damp day after day, or they get smelly, REI isn't going to tell me to put on some rubber gloves. They'll just refund my money. After a week of use, a month, a full winter.
I personally believe, as an opinion, that small, relatively unknown makers of high-end "boutique" products, should offer "full satisfaction" policies. Buyers of these goods are investing serious coin, and know how to use equipment properly. You have to trust them (the vast majority). They can provide invaluable information when they return goods and state their reasons for returning them.
For example,when DiNotte entered the bike lights market, they did this. They were unknown relative to cos like NiteRider, L&M (a fairly recent entrant in biking, but long established in UW photo-video lighting), et al. DiNotte offered a "full satisfaction" guarantee. Buy selling premium-priced products to serious enthusiasts, they got invaluable feedback for product improvement.
I bought a 600L light last fall. Less than a week after receiving it, I went to the DiNotte website and whoa! they had a new 800 lumen light that had not been pre-announced. I emailed them saying I would have waited two weeks had I known a more powerful light was out.
I had used the 600L, but it had no signs of wear. DiNotte said, "No problem, send it back, we'll take a look at it, and if it works and still looks new, you can have a free exchange. " (At the time the lights were same-priced). Basically, DiNotte "lost a little money" in that I paid for postage for return and on the new light, but not the original- purchase postage which DiNotte paid for, and in reselling the 600L, they had to inspect, test and repackage it, as well as ship it postage-free to a new customer.
Later a battery went dead. I had used it in temps ranging from 50s to just below 0 F, but one night it went out and couldn't be charged. I sent it to DiNotte on Monday, and Saturday I had a new battery. I paid $4 postage to return it, they paid postage on the replacement.
Fast forward, today we have DiNottes on three family bikes. I'm willing to pay "a little extra" for great products and superb "put the customer first" service.
As an aside, Jack Stephenson got into a protracted internet-publicized run-in with a customer ((who I believe worked at Caltech, maybe an engineer or technician)) regarding a customer- claimed product defect that Stephenson denied, blaming the customer for abusing his sleeping bag. That scared me off from buying a Warmlite bag, and I bet a lot of other people. The upshot was, the debate made it look like the buyer was a reasonable, educated, competent backpacker, while the seller was a cantankerous old curmudgeon, and ultimately, a disinterested observer like myself couldn't be fully confident the seller would stand behind his products. It would have been so much smarter, in my opinion, for the premium-tier-products seller (($700-$1000 sleeping bags)) to say, "You may have abused it, but you can either have a new bag or complete repair for free, or your money back." Buyers in this product echelon who would try to "rip off" the company would be so rare that the cost of placating them would be far less than bad
PR like this company suffered from one dissatisfied customer who was internet-savvy.
We bought a used Mercedes long ago, a "Baby Benz" 190D. After owning it for two years, and 4000ish miles past the warranty period, something broke. The dealer fixed it. My wife went to pick it up (they drove her). "No charge." Where do you think we purchased our next car? I can tell you my Toyota dealer doesn't do that, they denied repair on a part the shop manager said, "Oh yeah, these tailgate latches break all the time, that will be $217," nine months after the regular warrantee expired, and the part wasn't covered on my extended warranty either. If I had gotten a Lexus, it would have been a no-charge repair, and it probably wouldn't have broken in the first place (the std warranty is longer and parts quality is often higher.)