Own K-5 II, have had no problems

I've have the K-5 for about a year and it's behaved perfectly. I have a number of lenses including legacy
ones from my Pentax film SLR and never have had one problem. I've even used it in light drizzle and the waterproofing works.

I also have just bought a Samsung NX-1000, a mirrorless camera with a DSLR-sized sensor and am very happy with it. It's small, light, takes gorgeous photos, and is currently very cheap, currently $324 with a 20-50mm lens on Amazon. If you want a camera you can carry around all day with no fatigue, this one is it.