I have a laptop running ubuntu with a single SSD. Does it make sense to run it with ZFS to get compression and snapshots? If I add a hard drive, again does it make sense (perhaps using SSD as cache (arc?) )
The compression and deduplication features of ZFS is terrific on network filers. Compression could possibly improve performance slightly on a single disk system.
With two disks, I'd say you'd probably be better off with running RAID0 (or no RAID at all) and having a great backup plan. Using another SSD to cache writes to another SSD doesn't make a whole lot of sense to me.
XFS performs better out of the box on a wide range of hardware, while seemingly giving stronger data reliability guarantees (but not anywhere near ZFS's).
ZFS on a single disk, however, will still give you data checksumming, so you can detect silent data corruption. XFS's sole missing feature as a basic filesystem, imo, is data checksumming.
[1]: https://access.redhat.com/documentation/en-US/Red_Hat_Enterp...