I suggest wearing your rain jacket over the top of the waders and use a wading belt to seal the jacket to the waders. This way if you sit down in knee deep water, you may not get water flooding over the top of the waders ending a good day on the stream. This happened to me last winter and ended my day 5 minutes after I got in the stream and since I didn't have dry clothes, it was a cold drive home. I even considered a kayaker's dry top as the ultimate way to keep dry.

Rich