Solaris packages are easy to create, but getting things to compile can be tricky as lots of open source code assumes Linux-isms, so you have to port to standard

Solaris packages are easy to create, but getting things to compile can be tricky as lots of open source code assumes Linux-isms, so you have to port to standards. (BSDs have the same problem.) Zones are integrated into the very core of the OS, not bolted on. btrfs does sound like an improvement on ZFS in a few ways, especially in it's COW b-trees, taking advantage of a few more years of development. Competition will be good for ZFS, but right now, ZFS is probably the best shipping and stable FS.