I would say execution-wise i-no is still harder than eddie - but gameplan wise eddie is still harder than i-no.
To play i-no maximally you need to have the j.D FDCs. Those are actually pretty difficult to pull off consistently, it takes a lot of practice to work for all the situations you use them. Also, the IAD j.k combos on every character - which takes a lot of practice for the weird characters.
Zato's combos and mixups are not very hard. What's hard is coordinating Zato and eddie in the neutral to get your knockdown/pressure/mixups started. That is significantly easier strategy-wise for I-no to do.