Use rich Windows GUI with DevExpress to manage Debian and Centos server via SSH channel.

Linux has tens of thousands of very good open source programs supported by excellent programmers

Some Windows users are not aware about them and it is relativelly step learning curve to switch from Windows to Linux.

Having a convenient GUI to manage some program like OpenVPN, Firehol for office firewall, ZFS storage, e-mail server, etc. may be usefull providing such GUI has similar feature set to a comparable completelly Windows based products. Linux can be ran in a virtual machine to do its work, even in a cloud without installing on client side for some services like e-mail.

May be this can be done for Zentyal Linux Small Business Server