true we can never really be aware of what was never written down except that the sequence of recorded changes usually implies some form of demotic usage.

It is interesting to note that the 1511/1515 manorial roll is virtually 100% mac/ine for Manx names.
By the 1703 composition book probably less than 5% - I have extensive transcriptions for Peel where the mac/ine seems to be dropped between 1570's and early 1600's but at this time most Peel property owners had English names so bit difficult to draw conclusions. Thanks to Wally Corrin there are some transcriptions for Arbory which also show a considerable change around the the same period. Whether this was political (forced or otherwise), or a response to increased communication with England (fears of Spanish invasions, Irish military expeditions etc) I don't know - certainly judging from wills, reported court cases the ine form appeared to last much longer in reported demotic speech.