Motorola Moto X (Sprint, 1st gen.)
4.4
I'd go into apps and Force Stop non-essential ones.
After the first few charge/ discharge cycles following the Kit Kat 4.4 update, I am once again seeing 43 hours on average between charges on the Moto X.
As far as "going back" I always thought that Motorola devices don't normally permit a user reset to an earlier Android OS once updated.
At least that was the case with my Droid Razr when updated from ICS to JB.