A feature I would like to see is to be able to use core fields as conditional triggers. This way i can have form elements that can be conditional based on their zip code, or organization, or even as a CB or Jomsocial field I have assigned to one of those.
I think right now the conditional fields can only be used with custom fields.
I fully support this enhancement request for DT Register. It should be in general possible to extend the list of JomSocial integration in the way that I can chose which of the existing core fields defined in JomSocial (or CB ) should be used in DT Register.
This is a missing fuctionality and would grade up DT Register in comparision with other event registration solutions.