So I started to consider Android. Anyone running Android on an iPhone?
The most up to date project I could find is iDroid http://www.idroidproject.org/wiki/FAQ. iDroid has no power saving features implemented yet, therefore (they say) expect a batt life around 2 hours.
Any other distributions worth considering?
This is all plan (c).
My plan (b) is to go back to an earlier 4.x update and see if that brings performance back to acceptable levels, or go further back to 3.x if I really really have to.