Lucas,
Shana and I discussed this and i wanted to provides some additional information for you.
There are many benefits to the locators created with the Create Locator tool over the Create Address Locator tool and I will outline some of these benefits below.
1. These locators support Address, Address2, Address3 inputs right out of the box so there is no need to create a composite locator for what you are trying to do.
2..They are faster and smaller
3. They have improved match quality and the ability to handle extra information in the text much better. For instance, if you have "Attn: Joe" in the input string, this will be handled much better in these locators.
4. Improved suggestions for interactive geocoding such as suggestions for intersections and verifying the house number when showing suggestions. Other improvements are the ability to get suggestions with a locator in Pro without publishing it to Enterprise.
5. Create one unified locator instead of a composite locator. You can now create a multirole locator that combines many datasets into a single locator. This allows user to combine Rooftop, street centerline, postal, city, etc... into a single locator instead of creating separate locators and combining them into a composite. This allows the locator to be smaller and not duplicate information across multiple locators. A mutlirole locator will also be much faster than a composite locator.
These are the highlights but there are more and we continue to improve these locators each release.
With regards to the standard set up input fields, yes, all fields will be displayed if you build a locator with only a city role because we have a unified set of input fields. Typically users build a city locator only to include in a composite as fallback so there is really no need to do that going forward because it will just be part of a multirole locator. In addition to that, the "SingleLine" input field can always be used simplified input for the locator, there is no need to use the multiple input fields.
Lastly, you mention "The only downside I saw with that is it requires 2 copies of the same locator, doubling the storage size." in the first paragraph above. Are your locators quite large? If your organization can't currently migrate over to the create locator tool, the workarounds above are probably your best bet.
Brad