BDGA uses field mode???????? Doesn't it render in like 1280x480 and downsamples that to regular TV resolution?
 
 
 
I think you are missing what defines field rendering. The whole point is that your front buffer (what is actually read by the CRTC) holds only one field of information. What you do with the backbuffer will on the other hand determine output quality. Early games rendered 640x224 backbuffer, which simply doesn't give enough data to generate any kind of flicker filter. At any given frame you only have half of the data available, hence you can't add the FF blur samples to ease the motion artifacts. And even fixed image will flicker when there are any lines of only one pixel height (that's what FF also does - reduce vertical resolution a little to avoid flickering).
 
BGDA backbuffer is rendered in 1280x448 which is then downsampled to 640x224 front buffer fields every frame, yielding effective 4xAA (1280x896 -> 640x448).
Sly Cooper most likely renders 640x448 backbuffer. Depending on their downsample method they either generate standard flicker filter, or 2xVertical AA (it's debatable which looks better), plus they add motion blur between fields to make it look smoother.

-1280*448 * 16 bits backbuffer
-color recovery dither
-pas le droit de chuter en dessous de 60 frames/s,sinon ca devient TRES moche...