SLOG may be useful for any number of HDDs… if you need sync writes.
If you’re using NFS to share data files like you would do with SMB, you may override NFS defaults and disable sync writes.
That depends on what you want to do with it.
There are regular discussions on home builds, less so for ready-made appliances (or then it’s about installing TrueNAS, not hardware).
The Aoostar WTR Max you’ve found is intriguing. Plus: ECC support and X710 SFP+. Minus: DDR5 SO-DIMM, no block diagram… and I’m tempted to throw the PRO 8845HS CPU in this column as well because it looks like massive overkill in a little NAS—and then I wonder which corners have been cut to reach the price point with that.