For editing purposes, the Provideo card might do you better. The files the PVR250 are simply dumped right from the output of the card, so there's not much to be done to make them better.
However, the PV256 only does video encoding, and uses an MPEG2 multiplexor written by me to sync & timestamp the audio/video data and write it to disk.
This multiplexor is what is responsible for maintaining audio/video sync on the PV256 (I spent an enormous amount of time perfecting it). So I'll take credit for that.
Audio/video sync is maintained by modifying the actual stream data, not by adjusting timestamps (which screws up some editors), so the PTS/DTS values are error-free. Also, each GOP of video is aligned with the audio stream. So you can edit the files on any GOP boundary and simply cut the audio there and still have perfect sync. Because of this, editing the MPEG2 files my mux creates is as simple as cutting and rejoining the binary data at a GOP boundary. It's REALLY easy to make a simple editor for these MPEG2 files because of this.