I have found that the EX3 will do this job for me. A camera recording a man speaking in 16:9 and showing it on a big projecter in 4:3 - simoultanesly.
If I record in 720-25P - will the composite output (576i) just split 1 frame into 2 fields or will it be really interlaced ?
Will there be a large delay through the camera to the composite out? - know I can test it but thougt maybe someone else had experience with this setup....

I don't konw about the interlacing, but the delay is negligible. I had to feed 2 house projectors at a conference last year from my EX1 and used a 4:3 center crop, while I recorded HDV signal to my firewiire recorder. Worked perfectly. I got 16:9, they saw 4:3 and the speakers movements and mouth motions matched the audio.

Great thanks- Seems that this will be the solution. If and how it´s interlaced will probably not make much difference on the projector.