[1] Doran's first point is misleading, because it is untrue. In SFL Theory, hypotaxis ("status differences") is a relation in iterative structures of the logical metafunction only. The source of Doran's confusion, as will be seen, is the model of structure in Martin (1996):
which unwittingly misconstrues the distinction between experiential and logical structure as the distinction between hypotaxis (the unequal status of nucleus and satellite) and parataxis (the equal status of multiple nuclei).
[2] As was the case with the multivariate vs univariate distinction, Doran again begins his argument on experiential structure with Halliday's first statement on the matter, instead of later revised theorising.
[3] To be clear, what Doran refers to as a 'flat' structure, Halliday (1979) terms a linear structure.