Intensional reference sets versus intensional ValueSets

With the support for ECL in definition of FHIR ValueSets it is possible to intensionally define (by filters and rules rather than listing codes explicitly) a ValueSet by

creating a reference set in a SNOMED CT (or extension) release and exposing an Implicit ValueSet based on the reference set
do not define a reference set and instead define the ValueSet directly using ECL (or other filters) as required

Both options have pros and cons. Option 1 for example provides a reference set in a SNOMED CT release which can be used by those consuming RF2 and not using FHIR whereas option 2 cannot. However option 2 provides some advantages as well, as the ValueSet definition can be reused and re-evaluated against other (perhaps downstream) SNOMED CT extensions, however option 1 doesn't provide a standard, well used way to expose the machine processable conditions defining the reference set content.

This page is intended to start a discussion and capture the groups thoughts on the pros and cons of both approaches and consider best practices when making this choice.

Invitation to contribute a list of Pros and Cons to this page.