I rendered using the 8 meg bitrate and HD-WMV settings with an m2t file converted to DV-avi by Cineform to HD-WMV and lost a bunch of contrast and color saturation and picked up a lot of "judder" on the fast motion stuff. I remember seeing a thread on this but I can't find it.
After several experimental renders and viewing on the big screen I had to use two pass CBR at 8 megs 100 % smoothing. It reduced the judder a bunch but it was still there on fast motion camera movements. The judder was not there on the m2t files from the Z1. Rendered both the M2t and DV-AVI to WMV with the same judder results. The color and contrast were fine with the m2t render but the avi was low on color saturation. The Microsoft HD-WMV samples were outstanding compared to the Vegas WMV renders. The 1080i 30P vegas renders to m2t are just fine. I would say the HD-WMV Vegas renders need something as they are unacceptable but don't know what.