But isn't basically what USD and Solaris bring into Houdini? I realize that they're still relatively early implementations of the technology, but they're bound to get better and more optimized. Houdini 19 must be right around the corner and I'm sure SideFX has been working hard to strengthen the Solaris context as well as make it more accessible for everyday users.

You mean USD and Solaris bring Clarisse in Houdini ? The time it takes me to setup/shade a barrel using USD I have a complete environment done in Clarisse.

Thing is that I really don't want to turn this thread into Houdini>Clarisse. I'm using both, with today version.

USD dont replace Clarisse, it's an other layer of annoying stuffs to deal with.