I do think the CPU sched would be an easy win: nothing is really computationally expensive *at all*, so I don't buy the "it'll take longer" theory

. The lowest power step is still in the 3 digits realm, IIRC, it's not slowed down to a crawl

.
And I'm assuming you're already bringing down lab126_gui, which doesn't leave much running IIRC (powerd? blanket? been a while

). You probably don't need anything else than powerd (if even that, I have a vague memory of it being the thing needed to handle power button events properly on some devices, but that's it), actually.
Someone posted an up-to-date deptree of the upstart jobs fairly recently, IIRC.