I saw today an article about the release of version 4.1 of google play services. Several improvements mentioned, but the most relevant for me was improvement of battery-usage. So I installed it an hour ago and ... In my current rom (Mokee Kitkat 4.4.2) in idle (with all communication on (bluetooth, wifi, 3G)) my Mi2S used to dissipate some 6% to 7% per hour. With the new apk installed, in the last hour it used 4% !!! Still not optimal, but a lot better. See http://www.androidpolice.com/2014/01/09/google-play-services-4-1-begins-rollout-with-turn-based-multiplayer-new-google-drive-api-preview-and-more/ for details.