Look, I'm sure that when the bike works it is great - which ever year (and will have most probably better suspension than later models, which were dumbed down).
The issue with 690 (probably all road going KTMs) is reliability. KTM takes quite a few years to sort their bikes out and I think 690 was one of their worst efforts in this regard - it took them stupidly long to get the bike sorted. And after all these years it still has outrageous shortcoming in leaking airbox, that can be fixed by yourself, but it is still disgrace that they wouldn't even admit it.
And this is made even worse by buying second hand when you don't know how the bike was treated and whether the known issues like airbox were resolved. The bling is secondary in this as if the bike breaks down it is useless. And I personally would be a bit worried about the racing cams - to me it indicated that this bike may have been ridden hard if the owner felt a need to increase already big power of 690.
So when I was buying one, I deliberately went for as new model as possible (I have 2014) to get most issues sorted (and the guys who work on this bikes and bitched about early models, seemed pretty confident in new ones - once known nigglies like airbox are sorted).
If you know and trust the owner and you feel he is honest with you regarding bikes issues and riding history, you may go for it (bear in mind that low mileage may be indication of the bike sitting with mechanics - I would ask that question specifically, as well as the one about whether the airbox has been sealed throughout bikes life/ or alternatively if it is using any oil). Otherwise I personally would look at much younger model, or ideally - new.