Thanks! I've actually been too lazy to get around to wiring up the apartment for 2.5GbE (have it planned for the summer), so sadly I don't have any good performance data. The HDD-based pools easily saturate GbE though. It also deals just fine with concurrent sequential/random workloads like copying stuff while running torrents. Currently sitting at pretty much exactly half a year of uptime, so stability is also excellent.
I left that at default. I don't think I ever looked into what that option did, or if I did I've since forgotten - way too much to wrap my head around every setting at the time I was setting this up. From some quick googling it seems that setting sync=always can have some negative effects on performance? I doubt that would matter to me, but this also seems to be a setting that can be changed at will, so I might try it out given that 'always' should be marginally safer. Then again, writes to my backup drive are relatively rare, and I have a UPS, so it's extremely unlikely that I'll see any data loss from an unsynced write.
