Just recently becoming curious about the 950/990 Adventure...
But is that something enough for that one bike to replace both the GS and the XTR? 
).Probly agree.
With the 990 now piquing my interest, the only way I could make one happen for myself would be to ditch the GS (hitherto regarded by me as my forever bike), and my XTR, which is a revelation for me for riding off road (compared with the GS and considering my off-road skill set).
If I could have the 990 but not lose the GS and XTR, I'd love to try it for a while... but to be fair, if that doesn't happen, I still love my GS and XTR, so I'm not "without".
Anyone chosen a 990 or 950 after an R1150GS? Regrets? Best move ever?
I've been riding 1150 Adventures for a lifetime. But like the OP I have a strong itch for a 990 Adventure. My 1150 Adventure lives outdoors and I'm concerned that a KTM might not like not living in a garage. But I have no foundation for my fears.
Does Sir recall his search for the GSA and how a casual glance located the one you have .......
If you sell you will never get another one as nice without paying a premium

I went from a R1150GS to a 950 adventure S 5 years ago.
I loved the GS, the only thing against it was that it was just a little slow.
The 950 still puts a big a smile on my face, has been reliable and is one of the most fun bikes I've had on 45 years of biking.
A bit fiddly to work on, mine has had a few issues along the way,the most significant of which was the fuel pump (common problem - easy fix).
I've done wheel bearings, steering bearings chain and sprocket, wear n tear in my view.
Checking and adjusting the valve clearances is a bit of a mission but pretty straightforward. Doing this job yourself will save you a few quid!
I love this bike! Full of character and brilliant fun.