yes, you are basically saving as a jpeg file at that point.
In fact, jpg may be the BEST preview option because it provides 24 bit color — vs. 8 bit by the other Mac preview— and it compresses! The only downside is that you need Quicktime to view this preview.
(I'm assuming the "high end Contract Proofer is a Postscript device.)
yes he said preview but he also mentioned encoding, which I was referring to. But Doug has a great point that there is a difference between the 2.
the preview doesnt affect the file itself, but the encoding does.
One of our "Design" clients uses jpeg previews and encoding so that their illustrator pagelayouts are small and print fast to their proofer. Yet on their work order they instruct us to resave as full eps's which can quadruple or more the file size. Then they complain about the added processing cost at the back end...
If it works, go for it. If it doesn't ... Wait for it...{ and the bill}
I used to be of that school of thought, but I have since changed my mind after seeing it in real life.
with actual 'real' images it isnt that bad, but gradients can suffer drastically.