Not sure how other cameras handle it, but the GL 16:9 mode (which comes out great) previews horizontally "squished" in the LCD/eye cup. Is there a way to preview this kind of signal at true 16:9? Thanks in advance.
You'd need an external monitor capable of 16:9. Vegas can display it correctly. With the flipout LCD screen on the camera (if it has one) you can get an anamophic fresnel lens king of thingy to stretch the image to 16:9.
You should be aware however that not many cameras shoot true 16:9 and unless you have one you can achieve the same result in Vegas. Doing it that way however you need to be aware of your framing as you are going to crop the top and bottom of the frame.