Amateur Photographer published a review about Sony Alpha 900 in a 9 page article. It is an in depth review describing build, handling, white balance, color and dynamic balance. An extract of the review regarding the Sony Alpha 900 noise performance:
The problem (Sony Alpha 900) is noise reduction. Chroma noise can be seen sneaking into low-contrast areas of images taken at ISO 400, and even with noise reduction turned to its lowest setting, detail appears to be smoothed slightly in JPEG files. Oddly, noise reduction is also applied to raw files, which means that anyone shooting in raw+JPEG mode is not capturing a completely ‘raw’ image alongside the JPEG if NR is turned on. I would say that beyond ISO 800, the advantage of the Alpha 900’s many photosites is steadily eroded by noise reduction.