Well, I decided to give it a try anway.
I'm not sure whether it worked however.
I set the frequency to 33Mhz. The Iliad did a short screenrefresh and then everything continued working as normal. I'm not sure whether the process really worked...
I loaded a PDF file (took a while, but I think not longer (or not much) than usual. Page-turnings seems to work like normal too. the Battery-meter does not work (was full, now shows empty).
I'll leave the Iliad lying here until it dies. I started the Process around 13:30 German Time, the battery was not freshly loaded but should have been pretty full (battery-meter showed full...).
This will not be a clean and accurate benchmark, but maybe it'll at least give some insight.
Only trouble is that I'll porbably be fast aslweep when the battery dies...