My current setup is 3x Lenovo m920q (soon to be 4) all in a proxmox cluster, along with a qnap nas with 20gb ram and 4x 8tb in raid 5.
The specs on the m920q are: I5 8500T 32gb ram 256gb sata SSD 2tb nvme SSD 1gbe nic
On each proxmox machine, I have a docker server in swarm mode and each of those vm all have the same NFS mounts pointing to the nas
On the Nas I have a normal docker installation which runs my databases
On the swarm I have over 60 docker containers, including the arr services, overseerr and two deluge instances
I have no issues with performance or read/write or timeouts.
As one of the other posters said, point all of your arr services to the same mount point as it makes it far easier for the automated stuff to work.
Put all the arr services into a single stack (or at least on a single network), that way you can just point them to the container name rather than IP, for example, in overseerr to tell it where sonarr is, you'd just say http://sonarr:8989 and it will make life much easier
As for proxmox, the biggest thing I'll say from my experience, if you're just starting out, make sure you set it's IP and hostname to what you want right from the start... It's a pain in the ass to change them later. So if you're planning to use vlans or something, set them up first
