It will be indeed be interesting to see what other people get. My rig has no SSDs, decent quality SATA drives and showed the issue consistently since the availability of the 6.5 kernel. My workload is light, but quite consistent and with a typical workload I had IO loads of 40-60% whereas now (and with 6.2) they are (were) typically 2-3%. So for me, the issue really did show up with a pretty much idle load.