@DDPS maybe it would be a good idea to name some NAS models in your primer thread which have been proven to deliver decent performance. A lot of people seem to install RoononNAS on the unit they already own standing a good chance that this is an underpowered or outdated model.
I could offer some experience with different QNAP as well as Asustor models (consumer, semi-pro and pro-grade) and their pros and cons. Might be interesting for some people as Qnap is in my understanding ahead of the competition in terms of fanless and SSD-only NAS. It is a bit tricky as they are using a lot of different CPU models, limiting RAM on some or not offering additional M.2 cache slots in other models. So you really have to be aware what you are buying before installing roon on it.