As a hobbist - I use a PC with an Intel Core 2 Quad CPU and 8 gb with a 64 bit operating system (Windows 7) I down load using a card reader takes about 3 times as long as does the D3s files, but still not long at all (I'm a low volume shooter about 100 shots a day per camera at the upper end, usually much less). I use NX2 to only convert the photos a want out of a sequence and CS5 for the rest. (CS5 will open my D800e files, too).
This system worked just fine with big slide scans, and has worked just fine with D800e files. I even handicap it by downloading the raw files to external hard drives, and still everything works just fine.