Alright, after 94 hours I'm starting Milla's side. 9180 Grade, and I took quite a lot from the Grade shop :
Item x99, keep tool items, keep visual items, keep accessories, keep skill and arte books, keep special items, keep fell arms, experience x2, ingredient points x2, AC limit+1, keep arte usage, all skills 1SP. 9100 used with this setup.
Now I'm in the first field, and I'll stay here until I've grinded the title for 450 uses of Jude's Restore ability with those wolves. It was too hard to get my characters to get knocked down with maxed out stats in an efficient way for grinding so now with an average level of 5 it became viable.