Well Terry, "It Depends".

When sailing two up, with enough wind, I would probably put at least the crew out on the wire, but when sailing Uni, I have found it easier (more stable and less likely to swim) to sail deeper sitting on the tramp, way at the back of course, it just makes for one less thing to go wrong when it comes time for the jibe or to snuff if you are already on the tramp vs. out on the wire.

I did watch Matt and Gina sail away from me going lower and faster downwind where they were both in on the tramp and I was going higher/hotter on the wire, and that's when I decided to give it a try.

BUT...(there's always a butt, right?) as mentioned above, if you need to get up to make the mark, then by all means, get out on the wire.