It's all matter of how is it used.
While the internal EEPROM is probably truly bytewise erased and has the true endurance of 100kcycles, the OP needs around 9kBytes of it (and there is only 2kBytes).

Atmel claims 100kcycles for the FLASH too; so even if it is cycled cca 15 times while the whole "log area" is filled up in 9-byte records (128/9=14.2), it leaves >5000 full memory log cycles.

It is up to the OP, whether this is sufficient or not; he can make his decisions accordingly.

Jan Waclawek



PS. Erik, Atmel is not very clear how the internal erasing/rewriting cycle works, so it is possible (and logical) it does not erase if the bytes to be changed are already/still blank - that would make the "walking write" essentially the same as on other devices.