...the beauty of the AT is that I think it will tour well enough and then be able to hit the off road sections when needed...
I think this sums up the conclusion that I came to. Ideally I would have bought two bikes and a trailer (oh, and a car...!) - one a proper off-road bike and the other a tourer but I don't want two bikes filling up the garage (along with 6 bicycles!). I also prefer the idea of going places and not having to worry about the terrain too much - adventuring I guess. For example my dad lives in Wales where I can easily go riding in the valleys and hills -rather than load up the trailer I can just go and see him on the one bike. Same for heading off to Africa - or even Eastern Europe judging by some of their roads. The world is your oyster.
And rather than the Triumphs - which I couldn't get on with when I rode them in both 800 and 1200 forms - I was fixated on a BMW 1200 GS because it has a really nice feel to it - similar low CoG and rock-solid planted feel to the AT actually. But compared to the GS one was £11K and the other was £15K - and the £11K one was probably going to be more reliable and more economical to both fuel and service. It also had a gearbox rather than a random collection of cogs banging into other. At that point it became a much easier decision for me - in fact it wasn't a decision it was obvious there was only one choice (out of those two that is!).
Which tyres is a tricky question - if you are a really good rider that can push the limits of a road-oriented bike then you might reach the limits of the AT tyres but there are more road-based tyres available - even in 21" TT-suitable form. Fortunately I'm not that good although I do enjoy sweeping through twisties - I just do it at my own pace at the back of the group!
As far as I can tell it's impossible to get a bike that excels at everything. I think the AT is very good at most things (from 2 hours of test-riding with no off-road). And the DCT will assist me off-road where I'm a newbie. YMMV.
Not sure this helps you really?!