Apologies for the rant, I was a little ticked off that it wasn't working as advertised. The SkyDemon website had threads about the GNS units not being supported but I now realise that it's the GNS 2000 with it's GLONASS that isn't supported.
Now relaxing with a glass of Merlot and the iPad and GNS sitting on my desk I now have 0.0GS and an aircraft image sitting over my house so it appears that the nav function does work. If there isn't a Gale Force 10 across the strip tomorrow I'll give it another shot and let y'all know how I got on!