Thanks for all the replies and apologies for going AWOL on the topic for so long.
I like the idea of using the View Agent Direct Connect plugin option which sounds promising. As has been made clear it does really depend on how the VMs are being accessed (e.g. via RDP or for example a View connection using PCoIP). Our use case has not materialized but if another case arises I'll be clearer now on how to approach the use of either sVGA and sDGA.