> Many consumer SSDs ... under synchronous writes, will regularly produce latency spikes of 10 seconds or more
Surely "regularly" is a significant overstatement. Most people have practically never seen this failure mode. And if it only occurs under a heavy write workload, that's not something that's supposed to happen purely as a result of swapping.
Very easy to reproduce: 1. Buy cheap QLC drive. 2. Fill with Steam games. 3. Delete some steam games and download new games. 4. Watch write speeds tank to zero for long periods when downloading.
It's due to garbage collecting on very slow QLC NAND. You won't see it until the drive starts to get 60%+ full. Until then, the drive pretends it is an SLC with very fast writes, but then it starts to show its true colors. Yuck.
You're gambling on consumer SSD firmware not dumping the FTL and going AWOL when queued swap writes pile up under memory pressure. You may never see a 10 second stall in normal browsing, but add write-heavy Chrome churn or a VM and that 'never happens' claim gets shaky fast.
