I mean, that now The only way to choose between writeback/writethrough/none caching is to use virsh and edit xml.
The same for many other parameters like model (virtio/rtl8139), mac address, serial number of hard drive and so on.
This is available upstream, along with network model. I don't thing MAC address is something we want the user to just change at random, unless they are initially creating a new guest/network.
HD serial number isn't exposed yet, but could be added. please open a separate bug report.