Xtreme brushes are perhaps not for everyone, but I like my kit as light as possible. I use an Xtreme 22 pole as my everyday pole and find the Xtreme brush to be a perfect match for it. Without trying, I find that I work faster with this combination.
I also find that though the Xtreme brushes may not last as long, say as an Ultimate, they do last me a decent time considering the amount of work they do. I find that they are a worthwhile tool, for me at least.
I’m currently trialling a DuPont version which is very nice. Much better on leaded glass IMHO than any other mono brush I’ve tried, and I’ve got a lot of these on my round. As for longevity, I can’t say yet but I’ve been using it for a month now and it’s still in very good shape.