I must have been on beer binge. My xi 5 came with a 3 blade prop. Sorry for any confusion.I have ran both 3 blade and 2 blade on my Motor Guide.
My motor guide shaft is possibly a little short and I believe that the 3 blade prop would cavitate a little less on big wave days.
Couldn't tell you about speed or power difference, I know the new XI 5 came with a 2 blade prop but my spare that I bought is 3 blades.