I was using a K-3, K20D and Q when I bought an a6000 a few months ago, with 16-50mm kit zoom and the Zeiss Touit lenses (12mm/2.8 and 32mm/1.8). The a6000/16-50 has completely sidelined the Q, with its compact size and superior IQ. I still use the K20D with Sigma flash and zooms when needed, but the a6000 has become the backup to my K-3 when I'm carrying two bodies (which I do frequently). If I'm only carrying one body for general photography, it will be the K-3 and 18-135mm if there's rain or snow in the forecast. I have a bag that just holds the a6000 with kit zoom, and I have a small LowePro Event Messenger 100 that holds the body with kit zoom and Touits, or kit zoom and a telephoto.
Lens selection for e-mount is impoverished, especially telephotos. There's a slow 55-210 consumer and a large 70-200mm f4 full-frame. No tele primes at all beyond 60mm. A decent selection of primes 50mm and shorter is available. No f2.8 zooms, a couple of f4's, a couple of kit lenses and a superzoom. Very limited third party support, but of course you can use DSLR and rangefinder lenses with a suitable adapter (and manual focus). I have a couple of PK adapters from RJ, one with Turbo element that mimics full-frame with my A, FA and D FA lenses.
I bought the Zeiss 32mm hoping it would be as good as an FA 31mm, but it's more like my FA 35mm; really solid, not really exceptional. The Zeiss 12mm easily beats the DA 15mm Limited for sharpness across the frame, one stop faster, reasonable size. The extra wideness is a mixed blessing. The advantages for the DA 15mm are smaller size, lower distortion and better flare resistance.
The a6000 grip is extremely comfortable in my hand. I could not get on with the scrunched up EM10, and the Fujis are too large for what I wanted. A6000 menus and buttons are horribly clumsy to set up, but everything is there once configured. It's certainly no match for a K-3 or indeed any DSLR with twin dials, but this hasn't been a big problem. It looks like Sony stole a couple of Pentax features, allowing auto ISO in M-mode (TAv), and Program shift. I'm not an EVF fan, but again it hasn't really been a problem for my uses, and it's actually saved a few shots that would have been spoiled due to my error (e.g. incorrect EV setting). The tilt screen has come in handy a few times, but I much prefer looking through a VF whenever possible. Battery power is paltry.
I recently shot a wedding and used all three bodies. The K20D with 16-45 and Sigma flash on a sling, and in a messenger bag across the other shoulder, the a6000/32mm and K-3/100mm with ancillaries. The a6000/Zeiss had no trouble keeping up. I like the Face Detect feature, metering is extremely well judged, sharpness, colour and contrast very good. The shutter is significantly noisier than a K-3. The onboard flash is pretty wimpy, which is a problem for daylight fill.
All in all, I really like the a6000 a lot. Image quality is best in class when combined with good lenses, and it has features that are not available from Pentax, especially the compact size. Running two systems is a bit clumsy at times and certainly more expensive (temptation to build both systems). I would not be satisfied with Sony as my sole system, but I consider it the ideal choice for my uses as a backup/alternate/compact camera.
Last edited by audiobomber; 05-18-2015 at 12:03 PM.