The Trek Stretch Tight is fantastic, 10 / 10!It's light weight, warm, comfortable and I've never worn anything better.
I used them a lot while I was filming in China, they kept me warm during the long hours of standing around in freezing cold conditions waiting for film crews to set up for the perfect shot.
They stretch to the degree that they don't restrict movement and aren't loose in any areas, something I've found as an issue with many other brands of this type of pants.
Big thumbs up to Berghaus for these! I can't think of any improvements.