heartman, I didn't see your post when responding above. What you're saying makes sense. At this point I think I need to bite the bullet and have another audit company out. I was trying to avoid it since it's ~$500 for another company. She did have an IR camera during the test. I saw all the blue areas around the fireplace and kitchen bump outs and a lot of the exterior outlets. I also saw the blue creeping down the outside walls on the second floor. That's when she said my top plates were leaky. I think you're right that a smoke machine would help.
It's strange because even with the duct system being so tight, I still have those drafts. The duct blasting tech really wasn't sure why. He thought it was convection, my returns are only R-6.