I have the impression that Maks and KH do behave better if they loose Mytilene and Rhodos. They keep giant armies around that towns without doing something, which drains their economy and makes them very passive.
If they are however reduced to their island holdings, they seem to be more inclined on using naval invasions. It's kind of really rare with RTW.exe, but I have seen the Maks conquer Krete from Mytilene, the KH conquering Hallikarnassos from Rhodos and several times the Ptolemaioi Rhodos from Salamis, after being reduced to an island faction.
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