Nicotine can add harshness but it's not the only thing that can, as noted. PG does have more of a throat hit I'm entirely unsure if you'd find it "harsh" however and depending on your flavorings well some flavors can seem harsh to some people.
Best thing to do would be to try it I would think and see if you find it "harsh" or not. If you do, look at raising the VG ratio and modifying flavoring as needed. I'd say you stand a perfectly reasonable chance of it NOT seeming harsh however.
Is there a specific concern you have about the juice that causes you to believe it may be harsh?
Anna