According to dPreview, SONY now has six d-slr bodies priced at under $1,000. Wow! Six different choices! Not too long ago, I read a study that said when presented with more than four potential purchase choices, the typical response from the majority of purchasers was to make NO PURCHASE at all! None, as in "no sale".
It seems almost impossible to keep track of Sony's DX-body choices. And yet, at the top of the line, the A900 AND A850 are easily defined, and all alone. No morass of confusing model numbers and names, just 850 and 900. Very simple.
Sony is a consumer electronics company that bought a camera company's business and IP and patents, and is now selling d-slr cameras,so it's not too surprising that the company's marketing arm is making oddball decisions.