A modern GS is not a bike you want to have problems with, that's certain, as things get expensive fast. However, my bike has done 60.000km last week and has never needed anything. It'll get new clutch plates, though, as I've been advised to change them to improve the gearbox smoothness and as preventive measure against oil contamination fucking up the engine. Plates will be 300€ plus fitting, which is easy compared to previous generations.
It is frugal, I love the handling, the brakes, etc, and I really like boxer engines, no other engine I would rather have for the riding I like to do. Also, when I bought it I chose it specifically with two up touring intended, and there is absolutely no other big trail that can do that better than this bike, period.
Would I live with a Super Tenere? Surely I would, and I would love that if I had one, and maybe it would last longer too. But I like riding my bike a lot more so that's what I do and just put up with the risk of fixing it.