I have been curious on how magic luck works at item drop rate level. It also effects the quality of the stats once it is rolled, but i did not test that, as it would require thousands sample size to have any statistically significant result. I also did not test if drops/kills ratio changes with magic luck.
So, here is the result of 1022 item drops sample test.
Test setup:a- Level1 char, 0 magic luck - 461 drops
b- Level1 char, 7 magic luck - 561 drops
both chars re-rolled once they are lvl2. so all stats below are lvl1 drop rates to keep things controlled.
Observations:Magic luck effects drop rate of normal vs magic-unique
a: 50,2% normal drops, 49,8% magic+
b: 45,1% normal drops, 54,9% magic+
Magic luck effects rare chances:
a: 12,4%
b: 14,6%
Magic luck has no discernible effect on mystical+ drop rates, at sample of 1022. Probably bigger sample is needed to see. This also implies, the effect is less than 1 percentage points. You will see in chart that ML0 even seems to do better on angelic, which is unexpected. This would probably be corrected if I had more sample.

Magic luck effects also the tier drop distribution, albeit slightly:
a: 60,2% tier 1
b: 56,9% tier 1
Conclusions:If you were to run a +7 magic luck constantly, you can expect ~10% more magic+ drops (from a: 49,8% to b: 54,9%), assuming magic luck effect remains same for higher levels.
Likewise, you will see higher tiers drops more often, in this experiment tier3 was highest possible tier, and increased by ~5% (a: 6,9% to b: 7,3%) that is 32 items vs 41 items on their own samples, so it is significant, but can be slightly changing at larger sample.
Regardless of magic luck, drop rates of arcane+ is ~ 2%, at 7 magic luck not much effect is visible.