Significant artifacts when rendering HDV to XDCAM (.xif)
 

When rendering native Canon A1 HDV clips (1080 50i 25 Mbps) to XDCAM .xif (35 Mbps VBR) in Vegas 7e (no filters activated) the render shows compression artifacts (i.e. edges, reds). These artifacts are not visible when rendering HDV to HDV (which, in Vegas 7, is no smart rendering, but recompression and compression).
I was expecting it the other way round, since XDCAM is said to be the better codec.
Can anyone confirm this and/or explain? Thanks in advance.