It seems that the latest update to the Facebook app made Facebook Messenger an optional component. This seems to have greatly reduced the app's battery drain, as I never have (nor do I plan to) use Facebook Messenger. I'm also in the habit of checking my battery stats to make sure Facebook isn't running when I don't want it to. I'll either force close it or task kill it when I'm done.
I've been running LG Notifications since I rooted my phone. It didn't significantly drain my battery. And this is on rooted and de-bloated v4, rooted and de-bloated v6, Broken Out Spectrum 2.0, and Broken Out Spectrum 3.0. I have the app running as a service right from boot; notifying me of emails, MMS/SMS, and missed calls. I customized the notification to flash on for one second, then off for three seconds, starting immediately. I have it set to timeout after one hour.
Maybe I just don't receive as many emails or texts and miss as many calls as you popular people...