You are correct that Nikon uses Sony sensors and then do processing in camera before the RAW is written to the CF or SD card. Canon produces their own sensors for their DSLRs and they provide RAW images un-processed when written. This is why astro-photographers use Canon almost exclusively. You can use Nikons, but have to turn the camera off immediately after the shutter closes so that the in-camera processing is bypassed.I see there's still no love for the Sony/Minolta :-P
A lot of those high end, full frame Nikon and Canon cameras actually use a Sony sensor. I'm heavily invested in Minolta/Sony glass, some of which goes back to the mid 80's, so it doesn't make much sense for me to switch at this point in time..........sort of like why I won't be trading my Jeep Wrangler for a Bronco any time soon.
Sony makes good cameras and their glass is very good. Good that they are pushing Canon and Nikon to continue to innovate. I won't be trading or selling my Rubicon either. It is the best vehicle I have ever owned and I dread driving any other vehicle we own.