I too render to .WMV and have also observed some undesirable behavior from Vegas Pro 11 – most importantly file sizes are bloated. I was having a problem with rendering to .WMV and file sizes being much larger than they should be so I ran a test. I have a .WMV file I just dropped on the timelne and rendered out to .WMV. All the parameters of render very close to source except bit rate (which was LESS on vegas rendered version than original). The Vegas Rendered .WMV had 11% less bit rate yet a 250% larger files size. I also reported this to Sony Creative Software Inc but have not gotten a response.