I am cutting some 1/2" Hardibacker into some 2" x 32" sections. I tried using a 6 TPI wood jigsaw blade but the blades are not lasting very long. Does anyone know if a diamond tipped or carbide tipped would last longer?
Score with a utility knife, clamp between scraps of wood, and snap.
If you don't have enough extra length to snap with, the best tool I've found is a grinder with a diamond blade. (Use outdoors with appropriate PPE.)
If you have to use a jigsaw blade, then yes, the grit ones will certainly outlast a wood blade, but not by much. (And maybe not enough to justify the added cost.)