JDhm,
I have the Tersa knives mostly because the Xylent head was not an option when I purchased the machine in 2007.? I have used the M42 knives since 2007 and they keep an edge longer than I expected.? I typically change edges when I feel more resistance when jointing (this is hard to quantify).? For my hobby use, I go through both edges on a set of M42 knives about once per year.? These knives handle over 98% of what I have thrown at them but it does tend to chipout with curly maple, birdseye maple, and quilted white oak.? If you do a lot of figured woods or species that are very hard on knives, I would probably opt for the Xylent head.? Like David mentioned, another consideration is the capacity of your dust collection bins.? If you have large capacity bins, the Tersa would be fine but if you have small capacity, the Xylent could be the better option.
Steve
