Even the K-5 IIs is a significant improvement for me (in AF performance) over the K-5. I got to briefly use a K-3 last weekend at an indoor event, and it seemed even better.
My take is that either one (K-5 IIS or K-3) can do the job, while the K-5 is a little frustrating. Also, unlike with other brands, Pentax has put so much effort into improving the screw-drive AF system over the last couple of DSLR generations (because their future plans still include many screw-drive lenses) that a screw-drive will often outperform an in-lens motor with the latest bodies. So lenses like the Tamron 70-200 and Pentax screw-drive primes are realistic (or even optimal) options if a little focusing noise is not a problem.
Of course you'll have misses, but in poor gymnasium lighting you can still do well. I haven't sorted these all out yet, and may still need to adjust exposure since these in-camera JPEGs went straight to the web, but my K-5 IIs (which has also done well outdoors) did the job indoors last Friday:
Top Photos - EventTime Photos
Most or all of these were taken with the F*300. I took a few with the DA*300, but I had more trouble with the AF.
Last edited by DSims; 03-25-2014 at 12:18 PM.