My approach starts from morphology, taking into account the phonological processes, even seemingly low-level phonetic processes that are at work between host and enclitic pronoun, and is somewhat lexicalist of character. The research had as its aim to enlarge and articulate the factual base material, and is in that respect theory independent, albeit theoretically informed. That is, according to the developments of that time.
Map 1 from MCGG (Goeman 1997)
• Postma (2006) concludes that what lies at the origin of Comp-agreement is a combined extraction of the nominal domain (as in Goeman 1980: cliticisation from the structural subject position), as well as an independent inflection of the C-position in the extended verbal domain (Zwart 1993: verbal domain with C- and I-inflection).
• De Vogelaer et al. (2006) seems to be parallel at this conclusion by Postma. Because, according to them, neither morphologically inspired nor syntactically inspired explanations of the phenomenon of Comp-agreement do exclude each other; there exists a chronologically later syntactic restructuring of the primarily morphologically characterised structure.
My research into inflected complementisers was also connected to research into verbal inflection and pronouns. With respect to dialects of the Netherlands I reported on present tense inflection (Goeman 1993) and on the uniform present tense plurals in -t and -n (see the page with books and articles). For the whole Dutch speaking linguistic area see the two chapters on present and past tense, and on personal pronouns and enclitics in MAND volume II (2009).
To the Comp-agreement articles I add two articles on 1st singular present ik ben/ik zijn <I am>, and on 2nd singular present inverted doe je <do you>. These monosyllabic verbs show aspects that play also a role in the inflection of complementisers.