Looking for old Heirmoi

Does anyone know about any exegesis done by the Three Great Teachers (or at least done by someone who lived in the 19th century) of the old Heirmoi found in Heirmologia before the Daniel the Protopsaltes?

It seems that the melody for the Heirmoi is completely different from what we have now, and that there were lots of changes during the multiple centuries.
Do you think that the Heirmoi were read in a quick way, similar to how we read our scores for the Canons nowadays, or do they require a slow exegesis, and were sung as Kallophonic Heirmoi, similar to the ones we have in the Heirmologia Kallophonika?
 
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