Carbide!
I did a bunch of work in a housing development back in the woods of upstate new york. The fella who cleared the properties just dropped everything, and pushed the whole trees into a pile in the corner of the property. He did this at every home site in the development. The houses that were being put up were 2+ million bucks each, so the HOs didnt really enjoy seeing this massive pile of brush and trunks behind their houses.
I bought 4 carbide chains, 2 for my 440 w/ 28" bar, and 2 for my 066 w/ 36" bar. They cut great in dirty logs- these were sometimes covered with dirt from where the dozer pushed up the pile. I did actually have one of my guys cut all the way through a 4" rock without realizing it. He should have felt it, as he trashed that chain.
All in all, worth the money if you have the need for carbide. They do cut slower than regular full chisel or chipper chain, but they will cut some real nasty wood that would otherwise destroy a regular chain.
Got em hanging up in the garage now, haven't had a need for them since. They paid for themselves in one day cutting through that mess though.
:greenchainsaw: