The only sniggly issue I am aware of on these bikes concerns a jackshaft in the engine that has a tendency to wear or break somewhere in the 150K-200K mileage range. My cousin's bike, which had otherwise managed over 250K miles with him with only a clutch, a fuel injector, and a final drive replaced over that interval (aside from tires, bulbs, oil and filters of course), finally succumbed to that malady. The shaft is waaaaaay inside of things, and the part costs a few hundres of dollars and requires alot of presses, pullers, etc. and labor to replace - it was alot easier and cheaper by far to just buy a low mileage donor engine.
They do go like a cruise missile. I *almost* bought one before I bought my Kawasaki concours. I like the concours slightly better for the fairing it comes with, and I think it handles just a tiny bit easier. But the K100 is still a solid, fast bike.