Thanks John …. I have tried Boris FX (trial) …. their ‘light wrap’ feature does work well, however, I have problems with Boris* (apparently) not being compatible with the video card in my notebook (which I often use – immediately freezes either as a plugin or standalone).
I had the most success with (on difficult keys eg translucent hair) Cinegobs (importing with Avisynth) … & importing the keyed file back into vegas as a png image sequence. I felt I was able to get a better result than with Boris FX.
To be able to complete the process within Vegas with the equivalent of light wrap, certainly for some backgrounds would ‘sell the shot’.
* apart from an initial standard response Boris support failed to respond.
Graham