Hi Usman,
Thanks for getting back. The Network Load Balancer and Application Request Routing sound like they're worth looking into. I'm not responsible for designing the architecture of the new system - but I am working with the team who are so will run this by them. We will be avoiding DFS-R. We have had some problems in the past with DFS-R (specifically related to file-locking) and I have been told it is not current best practice. Though, as I say, it's not my area of expertise.
Cheers.