Any powermatic 221 owners out there with the 'quiet head' installed on your planer? I just scored one for free, and I'm curious to know if there is any compelling argument to swap out my 3 knife cutterhead for this one? I now have a grinder and plan to stick with this setup for a while instead of swapping it out for carbide. But I didn't expect to get this 'quiet cutterhead and don't know anything about it. Are the little knives carbide or HSS? Can it be sharpened with the grinder and if so how hard is it to do? Is is really much quieter than a 3 knife head that is properly sharpened and adjusted?

thanks