In my experience, luck does seem to affect drop rates.
I have two teams:
- My item collecting team - combining only the highest LUK characters
- My general battle team with:
- Characters better at boss battles in the back row (such as Vert and her multiple stat drop abilities)
- Characters who are good at boss or general battles (my beloved Noire ...shes good at anything...ahem not what I meant you perverts)
- Characters who can fight really well against mobs
I set these teams up because I had been trying to get a specific item to drop from a strong mob. I battled it literally 20 times, before changing my team setup from a team with luck ranging from 200-258. I changed to a team of all 300 and higher LUK, and got the drop first battle and in each of the next 3 battles, even though I needed only one item I checked to see if I could continue getting drops with my new luck set.
The only thing I'm now unsure of is if certain items require a certain amount of LUK before they drop, or if the drop chance was just so low that it was either impossible or next to impossible to get the drop with my LUK.
I do this with any item I'm having trouble getting; grab a team with as much LUK gear as I can pile on, and with a naturally high LUK, and throw them together. It really seems to make a difference.