I don't want to discourage experimentation, in fact it's really cool to see such projects, if nothing else because they promote knowledge of runtime embedded power management.

However I have a question: did anybody measure the increased battery lifetime with this mod?

If not, the first step would be to check how many days a specific unit (pair device-battery) lasts with the stock idle power saving and stock image, and then how long the same unit can live in idle with s2ram.

When i say idle, i really mean it, no usage at all, so this is probably for somebody with a spare / old unit.