Apologies if this is reposted. My last 3 posts in this string were received by individuals but apparently blocked from "sys-func (oz)"....This makes it clear that Halliday saw formalism as the dominant tradition in linguistics from its beginnings. His inversion is an historic step towards abandoning the form/content dualism altogether.
I think this further step will take longer, because the container metaphor, from which the form/content dualism derives, is so deeply enmeshed in modern thinking. Matthiessen 1993 explores the 'long tradition of regarding language as a vehicle, container or wrapper of thoughts which arise in the individual’s mind.'
SFL has abandoned the container model of language, but the form/content dualism it produced persists, re-construed as strata of 'wording' and 'meaning'.
 Rose's messages to sys-func were not "blocked" — there is no filter in place on messages sent from subscribed addresses, and the list manager (muggins) received no "bounced message" alerts from the system software. No-one is keener than the list manager to see Rose's messages, since he is the most prolific contributor of misconstruals to this blog.
 In SFL, form is a key component of the strata of wording (lexicogrammar) and sounding (phonology). Each of these strata is organised according to a rank scale of forms: clause, phrase/group, word, morpheme; and tone group, foot, syllable, phoneme. The "dualism" here is of form and function: functions at a higher rank (eg clause) are realised by forms at the rank below (phrase/group).
 A variant of a container metaphor is deployed in SFL as the content plane: the strata of meaning (semantics) and wording (lexicogrammar).
 The strata of wording and meaning are clearly not a reconstrual of "form/content dualism". 'Content' applies to both meaning and wording: it is what they have in common; and 'form' applies to both wording and sounding: it is what they have in common.
Cf Halliday (2008: 180):
Thus the lexicogrammar — linguistic form — dimensionalises semantic space; and the grammatical system network theorises this process.