Originally posted by aslyfox remember that the shutter count listed is an estimate by Pentax
Right. Your results may vary. I read a thread here on PF that some shutters failed at 60K and others were going strong above 200K. Do you shoot in predominantly hot or cold weather? That might affect shutter life. Do you take shots one at a time or use burst mode a lot? Do you use predominantly fast or slow shutter speeds? Do you hold your tongue a certain way, or is the Sun in a sunspot cycle? So many variables! I do think a 100K rating vs. a 200K rating is significant for comparison, but doesn't guarantee either camera will actually reach that number.
I bought my K-5IIs with about 30K on the shutter without hesitation. I rarely use burst mode, and don't shoot every day, so I expect the shutter to last for years. The K-5 and K-3 families were built as rock-solid flagship models. The KP has a well-earned reputation. Though maybe not officially a 'flagship' model, I've got to believe its shutter is of at least the same quality as the K-5's 100K shutter.
Originally posted by bobbyscon what are the problems that cameras with higher shutter counts run into?
My understanding is that shutter speed timing may start to drift. So, for instance, instead of 1/125 sec you may get 1/130 or 1/120 or worse. (Measuring actual shutter speeds is a deep rabbit hole to go into.) If your camera isn't giving you the 1/125 sec you expect your exposures may be off.
Originally posted by bobbyscon If a used camera has 10-20% of it's theoretical shutter life "used up", (thinking a K-3ii with 20-40K clicks), would it have any noticeable impact?
I highly doubt it, unless the camera had been used in extreme environmental conditions or had been dropped.