I'm a bit jealous man, that looks like an awesome hike rewarded with some amazing views at the end.
They always overstate the duration, It happens here too, I think as they average it out at a certain walking speed, I guess. I always come in at a faster time as do most although I understand the exaggerated time frame for those who may walk a little slower.
That third image looks like a scene from Game of Thrones when they went to capture the white walker north of the wall.
The difference between top and bottom was nuts - a lot of people coming back down looked a bit miserable - probably the ones with no gear - 90 mins at -2 ain't gonna kill you but without gloves in that wind it wldn't be pleasant!
I only bought a couple of pairs as an afterthought! But at least we had them!
Yeah, -2 for extended periods isn't fun. It looks like a great walk though, I'd love to do it.
I can recommend it for sure just not peak season!