I've had mine for almost 2 years now, and can't fault it.
To be honest though, if I was looking to buy now, I'd be seriously tempted by the Triumph.
A few of points worth mentioning.
The 800GS has amazing fuel consumption, I seriously doubt that the Triumph will get anywhere close. It will certainly need the extra couple of litres in its tank.
The optional luggage for the Triumph looks rubbish, you'd have to go aftermarket for panniers etc.
I recently had an 'out of warranty' claim for corrosion on the sump. Although BMW only paid for the parts, I'm lead to believe that Triumph never entertain 'out of warranty' claims.
If you do buy one, make sure it's insured fully comp, ideally with 'new for old', or gap insurance. I had a good look over the 800XC at the launch recently. I don't think it's going to take much to write one off. The screen etc mounts straight on to the headstock (no subframe). Any frontal impact is going to bend the lugs on the frame. Same goes for the pillion footrests. They stick out a long way, very vulnerable, and are part of the main frame. I can see a lot of Tigers being written off after a low speed spill. When I pointed this out to my local Triumph dealer he said 'they're steel, so can be bent straight again!' However, I'm not sure I'd want my pride and joy being bent straight without access to a jig. I'm sure most people will be saying that they're not worried because their insured, but you'll need gap insurance (not many people have this). I can see a situation where someone has spent their last penny on a new Tiger loaded with extras, and has spent over £8000. The insurance assessor will look at the book price (£7500ish), and knock off about 15% then the excess. Soon you'd be down to settling for £6000. You might be able to buy a nice used F800GS for £6000, but there won't be any Tigers out there for a while.