Hi !
Just wanted to share my experience with the famous DA* telezoom.
I've had a first copy for almost a year before the focus system basically died during a photo session (either manual or auto, focus was not able to move anymore).
I'm GLAD it was still during the warranty period.
So I got a new copy almost a month ago, been using it for like 5000 shots, and guess what... focus failure yesterday, exactly the same problem.
This time, I'll just return it and order the HD DA 55-300mm F4-5.8 ED WR instead (I would never have imagined).
No need to say it never crashed or shocked against anything. I'm using it for sports mainly, so always in AF-C, and I auto-focus threw the "AF" button on my K-3ii.
Other than this problem, that's occured twice, I really liked that lense for its IQ.
AF is decent, quite OK for the sports I'm shooting (with ONE AF spot, but adding more it becomes too slow e.g. for mountainbiking), for sure not as good as some Canon AF.
So this is it, deception in the air, had to give it a chance but the second failure just a month after getting the new copy was just unbelievable, I won't try a 3rd one