I've got a BMW, 2 KTMs, 2 Hondas, and 1 Yamaha in the garage right now and I've had lots of different manufacturers over the years.
I think BMW and KTM make great performing bikes but the idea that BMW is somehow more reliable than KTM is humorous. I've owned 4 BMW's in my life and had significant issues that caused significant cost to fix or inconvenience to me with all of them. In contrast, I've owned 3 KTM's and the biggest issue I had was the foot knob on the sidestand broke off and it was covered by a recall.
As of this moment, my gas gauge on the BMW doesn't work and the dealer will fix it but it will go out again in a few months. They don't have a fix other than replacing the same old failed part. Additionally, I just replaced a blown front shock. This GS has a whopping 10K miles on it. I'm really worried about the final drive on it after hearing one horror story after another and especially since they don't even have a drain / fill plug in the 2007 GSA because the final drive is supposed to be "a lifetime unit" without need for service. HA.
Anyway....I love the GS and am glad to have it....but if I was really worried about reliability, I'd pick the KTM over the BMW all day every day. (of course neither of them are in the same universe of reliabiilty as my Honda Goldwing)
All I know is I wiped out and dropped my used 2007 KTM 450 XC-W off a 20 foot cliff and I scrambled to the bottom....picked it up, started it and rode it back up to the trail and finished. I bought it used and abused that bike for 300 hours and a season of XC racing and aside from regular oil and air filter changes, the only engine maintenance was the valves needed to be adjusted one time at about 200 hours and clutch gasket leaked a bit and had to be replaced. (and I probably did fork seals about 5 times too)
That bike was one of the best performing motorcycles I've ever owned.....if that's the kind of "high maintenance" that you get from a KTM bike because it's so high performing....I think it's well worth it.
Oh...and I have to admit my Super Duke is excessively bad about eating tires. It's hard to get much more than 3500 miles out of a rear.