Ask them if they are OK with a Linux server in Hyper-V on top of a Windows machine.
Most customers unfamiliar with Linux are just simply scared that something happens and they don't know anything about it and how to fix it but are easier when it runs on a Windows base and have access.
Security should not be a concern on Linux vs Windows
I run several 11.0.4.7 versions out there and some 11.0.4.8 and all have basically no issues. It always depends what you use them for and what special devices, features and settings you have as they all work with regular programming that is not way out there.
Joe
FHandw, ACSS, ACIS