Note Running at Max EGT is not the max power point, it is 125f down on the rich side of peak.
Correct; and you pay for that. Approx 10% more fuel for the same speed.
Lycoming say at 65% power no damage can done by any cooling or mixture changes.
I haven't seen that. Where is it? It cannot be simply true anyway because you could cruise climb at 65%, heat the pots up to say 450F just nicely, and then cut the power.
I don't like the old "cruise climb" institution; it doesn't achieve anything at all, while delivering high CHTs which are hard to avoid.
I did flight tests, climbing from ~1000ft to ~7000ft, using various cruise climb profiles, using the constant-EGT profile (the best way), and using a full-rich profile. The fuel burnt during the climb was pretty similar for all of them, but the cruise climbs took longest to get there and produced the highest CHTs (actually pretty high values; manageable only with an EDM700 or similar). The constant-EGT climb performance was quite similar to the full-rich climb, but the latter would not work for high altitudes e.g. over 10000ft because the engine would be way over-rich.
I think "cruise climb" is an artefact of the goode olde days when you had no instruments and when also "over square" was not allowed because nobody understood that it is/was a meaningless concept in engineering terms
