I am ready to start a fresh new playthrough with Josh Sawyers mod on hardcoe mode. I don't know what difficulty setting I should put it on. I play on Master through all my Skyrim playthroughs (any build). So what in everyone's opinion would be the ideal difficulty setting for JE's mod playthrough?

I went with Normal, as that's my standard difficulty setting. On my first playthrough even that was a challenge, to get used to the extra challenge it provides. My first attempt in a playthrough ended with the geckos Barton Thorn sends you to clear out. Second attempt I was killed by Barton Thorn himself. Once you get a few more levels and better weapons and armour you could always raise it.

That is true, thanks for the reply