IMHO, the advice so far has been misguided. Especially if you are working with DV footage (standard 29.97 interlaced, as opposed to any 24p pulldown stuff) you need to export WITH fields, or the exported render will never match the motion characteristics of any other DV material that the render gets merged with.
If you want to export progressive, working 60fps comps, that way when you drop that material onto a 29.97 timeline, the NLE will have full frames to work from to create fields with. If you want a still, you’ll have a full frame as well.
To say that field rendering makes motion look “too smooth” is actually complimenting the way fields works! In some ways, 29.97 is actually 60fps. Yes, but not really you are saying? Well, on an interlaced display (CRT TV for example) a render with fields will look double the speed of a render without fields, even though they are both 29.97 lets say… Agree?
jpb