Part of John K’s concern of using RAW (NEF) is the time to convert to JPEG for 1000 files or so from a wedding or similar.
Surely one can waste a great deal of time doing RAW-file Import into Lightroom or Aperture, and that might be a necessary workflow requirement step for some photographers, but it is also possible to convert RAW to JPEG, and go from there, perhaps saving off the RAW files for the 5 or 10 key images for which one needs the top quality (careful reconversion later).
RAW to JPEG speed
I timed how long it took to convert five hundred (500) Lossless Compressed 14-bit Nikon D800 NEF files into high quality full-resolution JPEGs, using the ACR batch convert function in Adobe Photoshop CS6.
While having 6 CPU cores is worthwhile, it’s good for only a 10-15% gain in many cases (with Photoshop and Lightroom, some other programs do better). The behavior is pretty much the same from Photoshop CS5 to CS6 and with Lightroom 3 vs Lightroom 4.
The 12-core results are from my upgraded Mac Pro, it is 3.33 GHz (not a typo). Results would be nearly identical to the 6-core if one were running a 2.93GHz Mac Pro, which is the fastest Apple sells.