Love it - I got a Byrd 8" cutter head for my jointer and ordered a new planer with the Grizzley helical cutter head. Both of them are quieter and perform really well.
The Grizzley cutter head came perfectly adjusted and has stayed that way. The Byrd cutter head was not so well adjusted. I've had to go back and retighten all of the cutter screws to the recommended torque. Once that was done - no problems. Since the recommended torque seems to be absolutely correct, I can only assume that someone at Byrd's factory was not overly concerned with using their torque wrench properly the day they made mine, or that their tightening robot was out of adjustment. So now both machines cut perfectly flat.
As a side note, rather than getting small ripples parallel with the cut, I now get very subtle lines perpendicular to the cut. They are perfectly flat - no difference in height, but apparently not perfectly smooth. On softwoods I start at around 120 grit to sand these out, but it takes 80 grit if the wood is really hard. Both the planer and the jointer leave these kinds of marks. On the whole, though, they're no worse than the ripples. The big advantage (besides the dB level) is the quality of cut in figured wood.