Hi there, Penny
I’ve just recently completed a project which had various sources, from DV to Beta to even, wait for it, DVD……. (which was awful). We also had huge interlacing issues. The final was to be shown on a 42″ flat screen in a museum and when I was completing the grade I used a standard broadcast monitor to grade. Everything seemed fine until I actually burnt the DVD and did playback on a HD flatscreen monitor. Disaster. Huge interlacing issues. Flickering, jumping, warping. We tried everything in FCP, shift fields filter, de-interlacing etc etc. Nothing worked. Our final solution was to run the entire Pro Res export through After Effects. Voila. No more stuttering or interlacing issues.
So, my long winded point is…. If you have material that you think may be an issue, test it first on the medium in which the final product will be shown. As a rule I usually work on a progressive timeline anyway even with DV material. If you’re experiencing issues with interlacing it may be worth it to run the clip through After Effects before you start editing rather than do the entire clip later.