Fair enough. My own experience with Silverstone cases has been that they have WAY too many screws, are fiddly to work with and invariably have some ill-designed details that makes them less useful and less pleasant to work with that they should—if only the designer had bothered to actually build a computer in his design. And, specifically with respect to NAS cases, that the DS-381 is a drive-cooking abomination.
I think that the CS-381 uses the same cage as the DS-381. Your CS-382 may have a different cage, which can only be good. But still 45°C is not great.
Genuine 2U rackmount chassis from Supermicro, Dell, HP, Lenovo, Mitac, etc. should fit the bill—but you won’t like to HEAR these, literally.
In consumer-styled cases, which may work with consumer-style quiet rather than server-style style jet engines, …
- Fractal Design Node 804 has decent cooling, is not so quiet (open top: HDD noise goes straight out), but does not have removable drives.
- Nanoxia Deep Silence 8 Pro provides a better access to drives (tool-less trays inside the case but no backplane), tough still not removable, decent cooling (not tested in the most stressful situation) and quietness.
I don’t have a fit for your requirements. Inter-Tech NAS8 looked interesting (and perfectly fits your requirements), but seems to have quite a few quirks and design flaws.