I got my camera back from Pentax repair after nearly 3 months.
I had the now famous double mirror flip issue on my K-r (seems it's even more on the K5) and after all this time being repaired, I am sad to say it is not fixed, well at least not if I'm using my original lithium-ion Pentax battery.. I know, weird!
I've read the hundreds of post on the matter for the K5 and everyone seems to agree the problem might be due to the voltage of those black batteries.
The one advantage we have over K5 in that case is the K-r can take regular AA rechargeable batteries.
So I tried using just rechargeables and so far, and by that I mean today, the problem has disappeared.
Here's a video I uploaded testing the camera with rechargeables and the stock battery, one after the other, the video speaks for itself.
I would like to hear from other forum members with the same problem, and if this "fix" will work for them.