But does OHMS support controlled vocabularies if I want them?

Yes! OHMS has a great system for incorporating controlled vocabularies into the indexing module. After creating and uploading a thesaurus into OHMS, these terms will be available in an autocomplete drop down menu in either the keyword or subject field depending on the type of thesaurus you have uploaded. This makes it very easy to choose the terms you wish to add to your index simply by typing a few letters and clicking the desired terms to add them to your fields. These controlled vocabularies only have to be as strict as you want them to be. They could come from the Library of Congress subject headings or could be created by your indexers as they work with a collection.