I have two #4 planes. One has a corrugated and the other is not. The idea behind a corrugated plane is less resistance. It might be a little lighter, not that you would notice. The reality is I keep both planes sharp and waxed, I don’t see any difference in performance. I think it was just marketing, back in the day. Today I don’t think anyone makes one, that should tell you something. If you find a plane that is in good shape and has a corrugated bottom, there is no reason to not buy it. I don’t think one is any better than the other.