I am replacing the cutters in my jointer and debating between high speed steel and carbide.
What are the advantages and disadvantages of HSS vs carbide jointer blades?
All else being equal, anytime you have a choice between HSS (high speed steel) and carbide, you have to consider the tradeoffs.
When does it matter?
If you're looking at long jointer knives, high-speed steel is a proven material, and if you happen to completely trash your knives by running nails through your machine, the knives aren't very expensive to replace.
If you're looking at a cutterhead with segmented knives or inserts, carbide is a good choice because at worst you'll shatter the inserts that hit the nails.