In the sense of explicit research into this? Not much, especially I'm not aware of anything regarding the demotivational effect of having individual votes stand

In the sense of explicit research into this? Not much, especially I'm not aware of anything regarding the demotivational effect of having individual votes stand directly against superdelegate votes. If you are just looking for information on the system in general, look for "Liquid Democracy", "Piratenpartei", "Liquid Feedback" (the name of the system used), and "LQFB" (acronym for the previous). Most of the info will be in German though. https://www.sebastianjabbusch.de/wp-content/uploads/2011/10/Liquid-Democracy-in-der-Piratenpartei-Eine-Neue-Chance-fur-die-innerparteiliche-Demokratie-im-21-Jahrhundert-By-Sebastian-Jabbusch.pdf https://www.sebastianjabbusch.de/wp-content/uploads/2011/10/... is probably the most thorough analysis you'll find, but the survey results have (according to the study itself) strong biases towards active members, the two surveys used different wording for questions so you can't make out trends, and it often commingles Liquid Democracy, the tool used, and direct participation in the party overall, which can make it hard to attribute answers to Liquid Democracy (IIRC it wasn't ever used in a binding manner). Regarding the biases, 65% of survey participants claim they don't use delegations (page 156 by the numbering of the PDF), page 110 and following shows how high the percentage of delegated vs. direct votes was.