What about a Suzuki?
Have you considered a Suzuki? I know one of your criteria is for a shaft drive, but a good chain drive with a scotoiler or similar is equally as good and requires similar levels of maintenance. The touring version of the scotoiler for instance has an oil tank which will be enough for between 4000 and 6000 miles between fills.
There are a few bikes in the Suzuki range you could look at, the Bandit GT being a fully spec'd tourer, then there is the new GSX1250F, which again if you go for the ST version is a fully spec'd tourer, although one of my personal criticisms is the fact that the hard luggage is quite small. Then there is the busa, which with some mod's to increase the bar height makes a superb tourer.
I know some people say the build quality isnt that great on Suzuki's and they are known for corrosion. What I would say to that is like everything, if you look after it properly, it will be fine. I currently have an 8 year old GSX750F K2 which has lasted well and is not quite, but almost showroom condition. Before you ask, yes, I do ride the bike all year round.
Incidentially, a few years ago, I went up to the Thundersprint in Northwich, Cheshire. On the Saturday they had a bike show at the local rugby ground where BMW had their full range of bikes which were available for a 30 mile accompanied test ride. I tried to get a booking for the F800ST, but someone pipped me to that, so I ended up taking the slightly more sports focused F800S for a run.
Comparing the F800S with my GSX750F, I found that the parallel twin of the BMW was lively, punchy and torquey, but not that far off the Suzuki I have now. The one thing that for me let the BMW down was the handling, maybe it was the standard OEM tyres but it didnt feel anywhere near as planted on the road as my Suzuki does.
The other thing that let the BMW down for me was the location of the fuel tank and filler, which is under the seat with the filler on one of the side panels just below the seat. If you were out on a tour and had a roll bag or something strapped accross the pillion seat, I would imagine it would be a real pain to fill it up as you would probably have to move the luggage out of the way first!