Did some testing on it here https://forums.elderscrollsonline.com/en/discussion/260647/willows-path-set-bonus-bugged#latest

If you use willow's path, you get about 15% regen bonus stacking on top of nearly every other bonus like 24% med armor passive, 30% battle rush, Mooncalf champion point passive, etc.

If you are using drinks, however, it works out to around 10% regen bonus instead of 15%.

Haven't tested whether it stacks properly with racial passives and mundus stones yet though

@IcyDeadPeople

Thanks buddy, appreciate it.