I just came across this thread and I'm the guy traveling rtw on the 500. Aaron Steinmann.
I get that it's not for everyone and some days slabbing it on long distances it's no fun but long straights aren't much fun on any bike.
Yes you can stretch your oil changes and I carry a spare no big deal only 2 liters to carry and really quick to do.
Filter every 2nd change.
As far as taking into somewhere remote any bike can break down and it's a pretty basic bike to do the little things on and I'm not a good mechanic just handy with tools.
You don't need to be a great rider to own it and it would be way easier to do the BDR routes and TET on than a big bike.
There is no perfect bike out there to do everything but there is enough to pick from that suits you , your attitude and riding. I picked this because I thought it would be a challenge and I like wheel stands
Just don't not pick it because you think it needs a piston every 100 hrs . Maybe if you are riding it pinned all day every day but we are talking about adventure riding not Dakar.
If you are going out camping for a few nights exploring the trails perfect bike.
I wouldn't of been able to go to as many places alone with a bigger bike just in fear of getting it stuck and or not been able to lift it out.
It's also handy to fit through doors for safe parking which opens up more accommodation opportunities.
I would like KTM to bring out a bike between the 500 and 690. Like a 600 little more oil longer between changes. Make it a little smoother a light subframe and cool Dakar style fairing. Kinda like a newer version of the old classic XR600
Oh btw I did do a full top end at 67000k and I would say most of your questions about it will probably be in my thread on advrider.com . Seat Concepts was the first thing to go on but yup some days my arse still hates me.