I think you are missing the point. Nowadays, what is the difference between a NAS and a PC ? Nothing. Remove the monitor of the PC and you have a NAS. No, your problem is that you are developing for the Windows platform, even using IIS as the web server for Daminion, so you simply don't have the expertise or resources for proposing something for the Linux platform which is the platform usually present in NAS.
Personally, NAS or not NAS, I would prefer to have the server part of Daminion on a Linux platform, same for the Web server. It is too bad you didn't choose Apache for the Web server par