Did some camera testing today so I thought I'd post the results if anyone's interested or researching gear to buy. I thoroughly recommend the Nature brand Fader ND filter as it has very little discolouration and as you can see it doesn't introduce very much softness at 200mm.
I'd normally do a colour grade but this footage is not graded so you can see what it would look like straight out of the camera.
Sony NEX-5N 1080p25 at 1/40 shutter speed
Dynamic Range Optimizer On: level 5
Sunset Picture Profile (Contrast -3, Saturation -1, Sharpness -3)
Daylight white balance setting
Tokina 80-200mm f/2.8 OM mount lens
Nature Fader ND filter 77mm
Transcoded to DNxHD 120 in Adobe Media Encoder CS5
Edited and titles added in Avid Media Composer 5