Hello
As an owner of a Dns-320L and having initially a lot of problems with it, I can only mention that the last months, it is running smoothly the Alt-F firmware. It turns on and off when I want and I do have ssh access always. While in the past for some kind of strange problem, (probably a Nand memory problem, seek this forum) this was not always possible.
One thing, the fan. Yes it is very noisy, and during this hot summer, it is almost constantly on, at medium level. But it is definitely too noisy.