I reduced the memory allocated to the networking and hardware VMs (sys-net 300 MB, sys-usb 300 MB, sys-firewall 200 MB, sys-whonix 300 MB) in order to be able to have more AppVMs active. Browsers gobble up memory.
Initially installed R3.1 but upgraded to R3.2 later.
Overall, works well. Wish I had VT-d. Also I wish I could have memory balooning in Windows HVMs.