You will have to read 350 pages on the Nordic forum though using Google translate. I did, but that is only because after visiting Leif and interacting with the others, I realized there would be something to learn and had context and knew the background and calibre of the people. But generally that's the summary, 4 of them have ended up with TAD 4003 and dual FLH, after visiting Leif I ended up buying TAD 4003 (never used stock) and dual FLH has been my favorite design for 4 years or so now.
I don't think it is particularly useful unless you know the sound characteristics of beryllium drivers like Radian and TAD vs non beryllium like Altec. My videos all over the place bring this characteristic out through videos, and I will have them together in my next write up. Some of Tang's videos show the positives of the TAD mids/highs pretty well. If you put on headphones suspending disbelief against videos, you will get the contrast.
A couple of AER videos bring out their highs well, though they have to be heard in person with Mayer 46 and red sparrow to appreciate the full range