When buying a jacket that uses a proven and well-known key component such as eVENT, I'd just check on the workmanship -- making sure the stitching and seam sealing are done properly. I would also check to see that it has the features I want at the weight that I can live with. The fact that the jacket is made by a newish, smallish company is of very, very little concern to me. What's the hang up about company size or history when you are buying a jacket? It's not like you're investing in an entire IT system...
Goretex's breathability is significantly INFERIOR to eVENT in large part because of its extra PU coating. You keep mentioning about Goretex having something similar... but the reality is that for whatever reason, Goretex has chosen NOT to go that route even if it means much-improved breathability. I think I can deduce why.
Companies like Integral Designs are much smaller -- and they cater to a smaller crowd -- hikers who give UL and breathability a very high priority -- and they tend to understand the strength and limitations of eVENT and are willing to abide by them.
In contrast, Goretex is really for the mass market -- from "real hikers" all the way to the proverbial "soccer mom". Ultralight and ultra breathability are perhaps not as critical as a garment that will last -- particularly since many wear their jackets 'in town'. In the mass market, many buyers expect their so-called "extreme garments" to be just as convenient, comfortable, stylish and dependable as any of their other garments!
Often, if you want "cutting edge" performance -- it comes with limitations -- and are therefore offered mostly by smaller, more specialized companies. But if you -- like folks in the mass market -- value brand and dependability -- then stick with the mainstream. Just understand that they generally can't afford to take the same risks as smaller outfits. The Goretex laminate itself hasn't changed much in the last 20 or so years. Writing on and on about other goodies that Goretex might have in their product lab is just a waste of time -- if Goretex is not prepared to bring them to market.