There is a review on http://www.reel-show.tv by Gary Adcock on thr PDW800. Just gone through the first bit and there are 2 errors already. He says that the PDW700 will do over and under cranking, and that the XDCam codec is I frame. Correct me if I'm wrong but neither of those is correct.
Mpeg-2 has the ability to use inter-frame and intra-frame methods for compression. The XD Cam HD codec is inter-frame (Long GOP) which is extremely efficient at this level. The Torino encoder found in most Sony HDV and XD Cam units can provide i-frame @100 Mbps, and if you want this ability you can purchase the Convergent Design Nano Flash SDI/HDMI digital recorder and set the bit rate all the way up to 280 Mbps.