From what I gather, not so much, depending upon the scenario. They are "faster than real-time", but then again, so is my (pretty ordinary in the scheme of things) i7 based desktop workflow without GPU acceleration. And they are limited to certain packages you may not want to use.
it depends on the scenario , but , in general , when used with the big iron video tools like Adobe , Avid or Grass Valley these boards rock.
see it this way : plugging a 1 GHz active probe on a 20MHz rigol scope with 6 bit a/d doesn't do a lot. Plug it on a machine that can handle it and a whole new world opens up.
These boards accelerate also during editing. instead of relying on the cpu to decode, apply the effect and visualize the card does the decoding. sure for a simple cross fade no problem. try doing a 3 point color correction, crop and overlay it on another corrected stream with an animation playing in the background ( think a newsanchor in the studio with an animated overlay (ticker tape) in front and a picture in picture. take in video and render real time without stuttering.
these boards have no problem with that.
I have an older Matrox card to do Hi-def. the underwater color correction is done using 3 point. i have a white slate with red green blue bars. i film this slate at 5 meters depth for a few seconds. then whenever i change depth i re-film it . this compensates for the loss of color. in adobe i pick the rgb points and the hardware card recolorizes the image ( it rescales the RGB spectrum ) . it does this on 6 videostreams in real time without requiring any rendering time. try that on a quad core and it already chokes on a single stream. render time required ...