If I understand correctly, the 9000 XL's have been out for only a month or two. They seem to be a major step up from my older 9000's. A "real gas shock", according to a local shop I have worked with several times in the past. On his recommendation, I decided to go ahead with a set. They're about $90 each, and there's a four for the price of three sale on right now.
Playing with them right out of the box they feel completely different. Haven't driven them a lot yet, but initial impressions are that they are way better. Much smoother and quieter ride, better control on rapid swerving back and forth.
Hope they hold up to towing the heavy boat.