Fred, although your question wasn't directed towards me, I'll offer my .02 worth.
The Byrd head doesn't scallop anymore than a knife head will. It's smooth enough but does require a few passes with a smoother plane afterwards.
Where it surpasses a knife head is you no longer have to pay attention to grain direction when you pass it through the jointer. The Byrd head leaves no tearout regardless of which direction you pass it over the jointer...even with figured maple. That saves time and a lot of mental fatigue.
The Byrd head produces smaller chips, so my dust collector works more efficiently.
Where you really reap the benefits is when you no longer have to deal with hours of tedious knife setting. And the carbide cutters last much much longer than knives. I hear 10 times as long as 1 HSS knife. Each cutter has 4 sides so in my estimation, I won't have to buy new cutters until I'm very old and gray.