[Ryan Bronz]"When using the DVX100b is there a difference in image quality shooting 'Letterbox' or shooting 4:3 and then placing a matte over the image in Final Cut Pro?
Not really and the added bonus is you can reposition shots within the Matte- much more useful than the hard matted shots. You'll typically have to matte a finished 4:3 letterbox sequence anyway because once you start any sort of color correction on hard matted shots it becomes obvious from cut to cut the matte is subtly changing as well. Much better to shoot squeeze mode BTW. 4:3 letterboxed looks fine on a 4:3 but horrible on a 16:9 display. Squeezed looks good on both.
I'd say 24pA as they can then be encoded to 24 frames per second web video with little fuss and all in progressive. In fact in general the only reason to ever shoot standard 24p is when you want to mix with 60i footage in the same timeline or are working with an NLE with no 24pA support.