It seems to me that the Yardmaker would work well for lawn start-up. As an aerator, it's better than nothing but you would be compacting soil more so than a good core aerator. As an over-seeder, it would seem to be of marginal help in getting seed-to-soil contact. I could be wrong. /forums/images/graemlins/ooo.gif
I've looked at them and they are well-built.
Just my take, here....I've always used a large tine de-thatcher to shallowly incorporate seed after broadcast for both new areas and overseeding. A drag harrow/chain harrow after broadcasting works for primary seeding, too.