Big Perreaux and tubed Wolcott's, both of which I owned worked well. The speakers were, I believe A3 or M3 (I'm a gear hound and get confused by the alphabet soup we audio folks live in) and had the PX upgrades.
They were as Albert described. I used mine with the old isobaric loaded Talon subs and they were awesome. In spite of the Wolcott raves you may find, I preferred mine with the quite pricy and hard to find Perreaux monos.
HOWEVER, make sure your environment is well controlled humidity wise. The same as a Ferrari, etc., I guess...high performance does make some demands. When the bias is set right, it can change as the speaker warms up and if/as your humidity varies during the day/week/season. Sometimes, I would walk into my listening room and the stink of ozone and snapping would remind me that I forgot to dial back the bias last session.
I live at the beach, so the constant tweaking and dialing in the sweet spot frustrated me to the point where I got rid of mine.
I should have spent the money to upgrade my room and HVAC: yeah, they were that good.