Days to write 16 GB looks like a USB 1.1 transfer. I would recommend using something faster. You might also destroy the swap snapshot (4.16 GB) as there is no point doing a backup of it.
Finally, if you really want to keep trying to work out a ZFS backup/restore of your system despite the bad experience you had, please experiment with a test system running the same Solaris release and that you can rebuild from scratch until you are familiar and comfortable enough with the process.
You might also have a look to this document:
ZFS Troubleshooting Guide - Siwiki