I think you will get more seed to pop with slit seeding. I am a big fan or aerating and overseeding though. Both is a great process. Topdressing it in is even better.
For the yards where you try slit seeding instead of aeration plus seeding, I believe you will have much better results if you add as a first step: mow lower than it has been mowed all season and remove all the clippings.