I use Nexenta, which uses the Solaris kernel, but with a Debian server-style userland, as a NAS. If ZFS were on Linux, I too would switch to it. Straight Solaris is like travelling back in time in comparison to the usual GNU userland, and while it's got nicely integrated ideas - like the services, logging and monitoring, etc., - the cost of being in a less mainstream branch is reasonably high.

At least with Nexenta, you have an apt-get which might work for some common packages. With straight Solaris, I have to go through all my shell scripts and only use POSIX options, etc., which turns out to be quite a pain.

We use Solaris 10. Which isn't quite the same thing, of course.

The Solaris kernel is excellent. The Solaris 10 userland, not so (except for the newer core stuff like SMF), and OpenSolaris is supposedly a Solaris kernel with a saner userland. But I'm yet to be convinced it is stable enough to run in production, and the new packaging system looks mildly troublesome.

And it's still difficult to get it to install without X.

I use it on a few workstations. It's a fine operating system, but I'm admittedly a bit of an enterprise UNIX head that's disenchanted with where Linux has gone. For the last decade or so, I've come to like some of the other free operating systems such as the BSD family and OpenSolaris.

I do, our webservers run it. ZFS with automatic snapshots has saved my ass quite a few times already. Sending incremental snapshots (for backups) to offsite location (another OpenSolaris machine) is also easy and efficient.

But, if linux had ZFS i'd probably use that instead.