Rating: 3 / 5
Test period - 40 days in Colorado Rockies. GF has the BPL merino UL tights, I have Icebreaker merino tights (yes, they weigh substantially more, but still under 200 grams).
At the end of the period, she has a run on one leg and a growing hole in the crotch. I have no wear.
Approximately 50 days of wear later in city conditions she now has multiple holes, and mine are still new looking.
In other words, these tights do their job well, but wear out quickly. In my opinion, it makes more sense to buy a slightly heavier, but slightly warmer product for the same amount of money and use it 3 times as long, than to buy the BPL tights.