i don't know. depends on how many tracks you have in your songs and on how many tracks you want to use the uad plugs. for me the duo is enough.
i use the normal logic eqs f.e. when i just want to do a low- or highcut. i don't think that a neve eq would do this 10 times better. like this you can save your uad power. in a normal project with about 40 tracks i use about 10 or more uad neve eqs, 2 - 3 uad comps, and about 2 - 3 moog filters and have still some processing power left. every uad plugin has also a "lite" version which uses less power from the card. and they sound more or less the same. same same but different
. i use them f.e. on hihats.
don't forget... some plugs like the manley massive passive use alot of power.
much more than a neve eq would....