The xtraview setup seems the way to go if you have a dualview or SD PVR already.
You go to the XtraVieaw "Setup options" page and you see some of the "layout diagrams" which simplifed things for me!
I then phoned DSTV's customer care department and grilled one of their consultants. I eventually got put through to someone who sounded like he knew his stuff.
What I came up with, seems to be the easiest way to go.
1) Get a HD PVR now before the price goes to over R4000
2) Price EXCLUDES installation (fine print ppl)
3) You can join your new HD PVR with the dual view or SD PVR via an RF connection. THIS is what makes XtraView possible. Your terrestrial antennae RF cable comes in from the aerial, and enters your SD PVR decoder and then the RF out carries "TV 2 + terrestrial TV" you then feed that "RF OUT" into the HD PVR decoder. You can then connect your HD TV via the HDMI and then your "TV 2" option comes from the "RF out" like normal with BOTH TV 2 channels.
4) LNB configuration seems to still be a mystery to the tech department at DSTV, but they're under the impression that one LNB goes to the HD PVR and another one goes to the SD PVR. This gives 3 independent viewing environments and TWO INDEPENDENTLY Recordable environments.
I have the sneaky suspicion that there might have to be a third or possibly even a forth LNB (ie 2 going to each decoder) to get EVERY CHANNEL independently on 4 viewing environments.