Testing the wrong way
It is oft said testing tweeters by listening to them is not very helpful, but here is a small result set. I was actually working on identifying a few odd issues in my measurement setup, but that is another story.
Anyway, I took 4 tweeters. $25 Vifa, $35 Viifa XT-25, $50 SB29 and the $90 HDS. Hooked them up through the DCX , 2K 48 db. Played some Joni Mitchel pretty darn loud. The more strident bits went exactly by price. Cheap ones horrible on peaks, the XT almost bearable, SB pretty good and the HDS clearly better. Watching on a RTA while playing, the cheap Vifa's were the only ones that showed any real energy above 20K, which is totally distortion as the DCX brick walls at 20K. I had already puled the cheap Vifas's out of a system and redid them with Seas, so I was not surprised. I have not been happy with the SB in measurements, but it sounded pretty good. No surprise the HDS is that good. It is one of the best.
This sure was not the best all around test process, but worthwhile none the less.