QLC have quite the write performance cliff though, which could be an issue during use or when rebuilding the array.

Just something to be aware of.

The 2.5Gbe network writes against a RAID-Z1 config of 4 drives puts the sustained write speed below that of most QLC drives.

Recovery from a lost drive would be slower, for sure.

Same response, basically: take a 1000MB/s drive, it takes 120s before it drops down to 20MB/s... where are you going to source 120gigabytes- on a routine basis.

Not saying premium drives dont have their place- but for 95% of people $200/TB ($100 premium over lower tiers) is a waste.