Jigsaw Blade for Hardibacker
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.)