[name_m]Porter[/name_m] [name_f]Millicent[/name_f] actually has a really interesting contrast to it, I like the structure of it more than I expected. [name_f]Millicent[/name_f] softens [name_m]Porter[/name_m] a lot and gives the whole name a more elegant, vintage feel.
On its own, [name_m]Porter[/name_m] feels quite masculine and surname-driven to me. I can see it in a unisex “surname name” category alongside names like [name_m]Fletcher[/name_m], [name_m]Sawyer[/name_m], [name_m]Parker[/name_m], [name_m]Spencer[/name_m], etc but like many of those it still reads fairly boy-leaning in everyday use.
As a combo though, [name_m]Porter[/name_m] [name_f]Millicent[/name_f] works better than I thought it would, the softness of [name_f]Millicent[/name_f] balances it out nicely.