No problem in criticizing the Thiels of course, but I can tell you they certainly are not bright by nature. They are incredibly smooth, the smoothest upper frequencies Thiel ever achieved, and smoother than the vast majority of speakers I know of. I have tinnitus with bouts of hyperacusis so bright or aggressive sound will never stay in my house. I can listen to the 3.7s endlessly and never get ear fatigue because of how smooth they sound (of course, helped by my CJ amps and a room with well controlled reflections).
My pal, who reviews, always thought Thiels were too bright but finds the 3.7s at my place anything but bright and fatiguing.
In fact, sometimes I even wish for a bit more "zing" to the upper frequencies!
Between the JA Perspectives and the Thiels, I find the Thiels upper frequencies a bit more integrated and coherent (the 3.7s are, in my home, the most coherent dynamic speaker of any size I’ve ever heard).
But the actual high frequency quality of the Perspectives, and JA in general, strikes me as more refined, pure and grain-free.
(BTW, I have older Hales transcendence speakers with metal tweeters and they are particularly non-fatiguing as well. I have not found the "metal tweeters sound like metal and are fatiguingly bright" thing to be an issue for many years now, vs in the 90’s when that may have been more true. I’ve had my ears burned by soft dome tweeters as well as metal, so I can never predict from the material what a speaker will sound like. Both my 3.7 and 2.7 Thiels, despite having all metal drivers, put out among the most organic sound - capable of round, soft, rich, delicate, as I’ve ever heard from a speaker. Which is why it’s been so hard to replace the Thiels, and why up until recently only the JA speakers
were, to my ears, contenders).
(BTW, I'm right now writing up a long post detailing all the speakers I auditioned, and my reactions, in looking for a replacement for my too-large Thiel 3.7s)