Thank you for sharing @Debbie! There seems to be great synergy between TaxonWorks and the work behind GBIFs vocabulary server. GBIFS and collaborators have been using verbatim values (and potentially old mappings) + counts to map verbatim values to controlled values for a bunch of terms, including DwC terms (be aware that not all are in production yet, though). We have a vocabulary API that might be relevant for you to use in further developments of TaxonWorks? We can discuss this at the conference, but you can access controlled and verbatim values, for example.
You asked for metrics on how the controlled values will improve data (searchability) and I plan to present this in the talk on GBIFs vocabulary server in the symposium.
Regarding the 27+ fields, are they listed here? We generate tables for each field and link to them in all issues when we construct new vocabularies.