Had a go myself, but found it a little cramped otherwise I would of probably bought one, I just could not see a scenario where I would of hopped on the GT over my 1190 Adventure, especially as local riding tends to be (often bumpy) back lanes and the small dimensions would not suit me for longer trips. Even took the Mrs to have a look at it, but she was not so keen and would prefer a 1050 / 1090. But she also has long legs, I think the GT is best suited to those with inside leg measurements of 30" or less, we are both 34" plus.
Anyone slightly interested in GT or that style of bike would be mad not just to snap one up now, if you don't like it the chances are in the middle of next summer you would pretty much get your money back.
If they had half that discount on the 1290 Adventure I would have bought one, maybe the same would apply to a 1090 for the Mrs, or £5k off on any two adventures.