I have recieved a response from the DVLA regarding my freedom of information request.
It appears that were 10 Oasis Green Falcos resisted in the UK between 2004-2011.
So it seems that there might still be more to find.
Who's/where are the 6 that are known to us?

The full document is available here.
As a side note, there are 283 Aprilia SL1000 Falcos registered (in 2011). 1 of which was first registered in 2010. 115 Falcos were SORN in 2011.