I base my assessment on my first hand experience, and the experiences of others whom I have observed first hand. Granted, kind of a small sample, but in it I have seen 100% reliability.
I also remember back in the early Twinkie days, when I was dumb enough to ride with the local HOG chapter. We had literally hundreds of members on the books, and probably a few dozen who actually showed up. Most didn't ride much, but many rode even more than I did. Most had the then new Twinkies, and were only HOG members who had received membership when they bought them. In that much larger group, I never heard of a single mechanical failure, outside of some of the infamous rear cam bearing issues, which H-D repaired under warranty.
And yes, indeed, there are plenty of manufacturers who absolutely make bank by selling products that "fix" non-existent problems. Especially in this day of the internet, where we see each and every "problem" magnified by internet forum types who ride their keyboards more than they ride their bikes.
The timing chest problems seem to only occur when running hotter cams. With the hotter cams, riders then rev the motor higher as well, which coupled with the increase in lift and heavier valve springs, put more stress on the cam drive. The cranks suffer as well when subjected to higher than stock revs. And somehow this seems to be a "quality issue" with H-D...
As with any hot rod motor, if everything is not done right, the weak links will soon be exposed. There is no shortage of riders who will put hot cams in it, maybe some Screaming Eagle heads, re-chip it to raise the rev limit and, if they are really industrious, put a big bore kit in it. All with stock cam drives and stock cranks. Then they proceed to hammer the bejesus out of them and wonder why they have problems. POS Twinkies...
