Has anyone ran Proxmox on an AMD APU? If so, does it complain. I understand I could also go with Intel or AMD FX, but for what I am needing a VM-machine for, doesn't require a Xeon.
It should be fine, the apu and equivalent athlons have the required virtualisation instruction sets. I don't however know how well proxmox will work with the gpu part of the chip but I doubt you'll be using it for 3D games so probably doesn't matter much.