I would recomend doing atleast a moderate amount of sanding. Ive looked at some of the odst peices, and because of the way they are made, in game and in pep, they wont need much or any bondo at all to smooth. Im planning on only using a small amount of bondo where there are large bumps, or on any peices that really need it. I also managed to make an odst thigh without folding anything but the major 90 degree type folds, which made it much smoother. If you look at the chest plates, theyre much more mechanical looking, so some of the folds are accurate. Now for my helm im going to smooth the crap out of that thing.