I want to know if 4.1 is set-up to use push notifications efficiently with regards to battery drain
Well the short answer is Yes, but this sounds like a misguided question. Push notifications have been around for a lot longer than 4.1 and to my knowledge there aren't any major "efficiencies" that were added to the Android OS after 4.1 to improve handling push notifications.
For push notifications to work, you need 4 components:
(1) An app server that's processing data for you in the cloud and wants to inform you about an event (for ex: Twitter/Facebook servers)
(2) A Push Notification Server that can receive requests from (1), figure out who its intended for, and dispatch a push to the right user/device combination (ex: Google Cloud Messaging server)
(3) A counterpart Android app/service that is always running in the background and has a persistent (always-on) connection to (2) so it may receive the push, figure out which app it's intended for, wake up that app and send it the small push data (ex: Google Play Store native app)
(4) An Android app that can receive this local data from (3) and figure out how best to inform the user about this push notification (typically by putting up a notification indicator in the status bar) (ex: Twitter Android app). This is what the end user thinks of as a push notification. Not all push notifications needs to show themselves in the status/notification bar though, they are sent silently by (3) and it is up to (4) to determine if a notification should be shown to the user
Ideally, even with push notifications setting turned on, (4) isn't awake. It'll be awakened by (3) when (3) receives the push from (2). Google provides the GCM framework that provides (2) and (3). So provided your apps are using GCM (or other equivalent services like UrbanAirship, Xtify etc), any excessive battery drain you might notice is the fault of (1) or (4), both of which are the fault of the app developer.
(1) and (2) maybe combined, as can (3) and (4). So if the apps you're installing have their own push service, that's still an issue with their code, not your device or the OS.
Additional reading: Google Cloud Messaging Architecture