I use supertweeters. These are SB Acoustics Satori beryllium tweeters I picked up. Purchased a pair of black plastic project boxes, used teflon caps from ebay, and binding posts. Made the "baffles" out of red oak from Lowe's. Inside, I have the positive leads from the binding posts and from the drivers with aligator clips which clip securely to the leads on the caps. This allows easy changing of them. Pictures below. I also have a pair less elegantly constructed using vintage Pioneer beryllium ribbon tweeters and a pair of baffles with vintage Yamaha beryllum tweeters that can swap with the Satoris on the project box.
I have them amped separately with 25 watt Temple Audio Bantam Gold. I use Roscoe's method of changing cap values for the roll off and output level to some degree, though the Bantam has a volume control.
In discussions with Louis, he encouraged having the tweeters not point forward. I have them pointed upwards. He said forward would affect the point source advantage of the Omegas.
They provide high end improvement when I'm using my Inspire SEP tube amp and when I use the Nelson Pass designed, but kit built ACA monoblocs. However, I acquired a First Watt J2 and found I don't need them at all. Using them degrades the sound, probably by providing too much high end frequency. If I were to use them with the FW, I would change the cap value to have them roll off even higher.