In reading over this thread, I was really looking at Sony for my purchase. A few months ago, I went through a decision process that led me to buy a k-x. Here is what this old red neck did, with emphasis on getting a 300mm telephoto setup for taking bird pictures:
1. Decided to move away from a super-zoom (older Panasonic 4mp 12x zoom with built in Leica lens) to DSLR.
2. Identified and narrowed down candidate list to Nikon, Canon, Oly, Pentax, and Sony.
3. Decided that I wanted the image stabilization in the body. Hence, that dropped out Canon and Nikon. Plus that eliminated those two higher cost options. I lusted over their 300mm telephoto options, but, the cost!
4. Of the 3 remaining, I was leaning heavily at one point to Sony, mainly because they had this older Konica-Minolta legacy and some sort of arrangement with Zeiss for various lenses. Example: Sony Distagon T* 24mm F2 SSM, as reviewed at
Sony Distagon T* 24mm F2 SSM Lens Review: 1. Introduction: Digital Photography Review
5. But, after cruising various forums, like this one, chose Pentax mainly because of my computations of price/performance. I got a brand new k-x with the 18-55 and 55-300 kit lens for about $600. That worked for my budget, and at the same time gave me very usable kit lenses.
6. My overall gut feeling was that while Oly was considered pretty good, I could not discern anything they had over the Pentax. Plus, I felt that Pentax, being an older camera company from way back, had a longer track record than Sony. Not hating on Sony here, but just to say I thought Pentax to be better.
Since I got my camera, I have taken quite a few bird shots, landscapes, and close-ups --- yielding very good (not great) pictures. To be honest, if I shoot the 18-55mm kit lens at the 35mm focal length, and stay with f6-f8 territory, the pictures are pleasing. Bird pics at 300mm, f8 are very good.
As it turns out, I found out after my purchase, that I could use all kinds of legacy lenses, like the M42 lenses, albeit in manual mode. Even tried an old Nikkor non-AI 28mm f3.5! Of course, I could get a Zeiss or Leica lens if I wanted, with Leitax adapter in the case of Leica-R and certain older Zeiss lenses.
All in all, as I look back, I do not regret the Pentax choice.