See this recent poll at a large German Pentax forum:-
http://www.dslr-forum.de/showthread.php?t=798146
(Google English Translation Here)
At the time of writing this Blog post, there are 47+62+10+58 = 177 votes input for the poll. Amongst which 58 users do not have neither a K-5 nor a K-r. But for those who have the two latest Pentax bodies with the SAFOX IX/+, the failure rate for accurate AF is 39.5%, whilst for those users who reported that there was no problem is in 52.1% and the remaining 8.4% of the K-5/K-r users are just uncertain about the problem.
In fact, quite some new K-5 and K-r users are still complaining about the AF accuracy of their new units daily, just see two recent examples here and here. For some more previous AF issue reports for the K-5 and K-r, just search here.
Related:-
Major Causes of Poor AF Reliability of Pentax DSLRs