So, i have ridden around 2500km on the bike with this jacket and i am still happy with it.
My regular layering system is: merino T-shirt, cashmere jumper, IHJ-79-BLK, leather jacket.
Down to 8C it keeps me warm up to motorway speeds (140km/h) for long stretches of time.
Below 8C i cannot sustain motorway speeds for more than an hour before i start to get cold.
At slower speeds (say 50 to 90km/h) i can go as low as 3C and still feel nice and toasty for hours at a time.
All in all i am really satisfied, only thing i would change is the A shape to a more V shape, but that's a problem i have with all IH tops.
I still don't think i could justify paying this much for a casual jacket to walk around in, but on the bike it has a bunch of nice features that really work well.
Highly recommended if you ride in the cold.