I voted for only grid formats and saved queries. I believe that, in spite of how convenient those other UDOs are to create, the outcome could be very bad if the creator is not very familiar with the ERP and the possible pitfalls of a poorly implemented UDO. Allowing an end user to use a UDO created by a knowledgeable person, on the other hand, is fine but creation - not so much. Grid formats and queries are "old school" E1 features and seem a little more user oriented, although I have seen occasional issues with those.
Developers are a good source to create UDOs but what I have also found is that some resources typically considered non-developers, like business analysts, can excel in the creation of very useful UDOs. In the past we have taken these through a similar change control process as more traditional development (Dev to PY to Prod) but with a slightly less rigorous process. Although not on your list, we treat E1 Pages the same way.