My experience with the Fazer engine is good.
Bought mine new in 2001.
It's now got 97,000 miles on the clock.
Still runs well, and I've never bothered adjusting valve shims or changing the cam chain..... I checked the valve clearances at around 35,000 miles, they were fine, so I screwed the cam cover back down and just kept on riding it.
The bikes been run on fully synthetic all its life, and I've added ZX1 oil treatment a couple of times...... I've never had to touch the engine, although I guess it must be wearing out.... pretty much like the rider really.