(symbol-access) reminds me of the property list feature [0] of Chez Scheme and other implementations (presumably R7RS as well), which allow arbitrary data to be associated with any symbol "in the background" (as I visualize it). I've pondered using tags stored in the prop-list as a kind of poor man's run-time type system for polymorphic functions to check before performing the appropriate operation, but chose to use custom record types, which generate custom (is-type-x?) predicates, instead.
For the more knowledgeable, is (symbol-access) a complete general purpose primitive for reactive programming, like (delay) and (force) are for laziness?