I currently own a 1050 Tiger (2007, not the new Sport). Also owned 2 Tigers before, a '99 and a '95 885. All great bikes, I'm a big Tiger fan.
Never ridden a 900 TDM but owned a '92 TDM 850 for two years.
I've ridden the KTM 990 ADV, not the SMT. I liked it ... but not as comfortable as my 1050 Tiger, uses more gas and not as fast or as smooth either.
I have no idea about the market or prices in Oz, but here in the US, used Tiger 1050's are some of best deals on the market. Really really cheap for what you get. If your liked your 955i ... then I think you may like the 1050 as a road bike ... but NOT for off road. The main thing about the 1050 is how FAST it is ... and how smooth. Nearly as smooth as your 800 Tiger. Can''t imagine how you'll deal with such a fast bike ... all my friends who've gone riding in OZ have come back with $2000 worth of speeding fines. Your cops apparently have nothing better to do than chase motorcycles. I couldn't believe the stories on this and how ridiculously SLOW your speed limits are.
I would NEVER EVER visit for a riding vacation for that reason alone. In California ... we like to SPEED. Why else have a 105 HP bike?
What it needs (badly) is suspension work. I've got an Ohlins shock and custom re-valved forks. Huge difference all round. I've only put 20K miles on it as I have two other bikes keeping me busy. One is a DR650 .... which will do BOTH of your required tasks ... if you set it up properly. But that's another story.
But the 1050 Tiger is a lot of fun, cheap to keep and reliable as the 955i or moreso. Good fuel economy, good twisty road bike and packs up well with Triumph panniers. Easy on tires, chains and sprockets too.
The Yamaha was a good bike (eons ago now) but I hear the 900 is WAY better than the original 850 TDM. Totally different bike? Dunno, can't help there. Mine was quite primitive compared to modern bikes and very very weird and dangerous handling.
The KTM 990 SMT gets fantastic reviews. I would for sure TEST RIDE one if you can. A lot more money than the Tiger, more maintenance and less reliable for sure ... but one Hell of a Fun Ride I'd guess.
But on a good road, I can easily keep pace with a well ridden KTM 990 ADV. I can out brake them, out accelerate them and out lean them because they've got a 19" front. The SMT has the 17" ... so better set up. Keep an eye on the water pump and the few other faults, should be a fine bike.
Two problems I've had on BOTH the KTM and my Tiger: Wind management.
Very hard to find a shield that is quiet. I only rode a friends 990 ADV ... it was noisy as Hell. Worse than my Tiger 1050. But it can be worked out with enough fiddling. A very short shield is best set up I've found .. I've tried FOUR different shield set ups. (see pic above)
Good luck.
(still prefer my DR650 over ALL of them!)