I've been using OpenMediaVault on a Raspberry Pi 2 Model B for over a year now. I find it works really well as a NAS. I do find that if attempting to stream anything from the NAS above 720p on my home network it buffers like hell. I'm happy with 720p most the time anyway, but if want higher quality then i'll stream in kodi using a real-debrid link instead.
I have recently brought a Raspberry Pi 4 too so might have to moveOpenMediaVault over to that and see how much of an improvement it is over the current one i'm using.