Share your optimal settings: Pros & cons of Exchange ActiveSync Vs CalDAV/CardDAV

So i've been having some battery annoyances lately, unrelated, but yesterday's google contacts/calendar/mail post by the impeccable Evan Rodgers, got me thinking about the basic set-up of services on an iPhone, especially since it was mentioned in the article and by Nilay in the comments as well, that the shift away from Exchange improves battery life considerably.

My recent battery issues notwithstanding, I havent noticed battery life being bad (specifically on Exchange), i generally get what i assume to be normal battery life, otherwise, nothing special, but not too horrible. Could it be that Verge editors specifically have a much more filled and actively changing calendar situation, combined with hundreds of emails a day, that for them Exchange with Push is more of a battery drain than it would be for normal folks? since the values of fetching calendar and contact data via fetch every 15min/30min/1hour were expounded upon briefly, is it possible that push service for contacts and calendars for someone who doesnt change his calendar or contacts many times a day, might be better for battery than fetch?

I admit, I know... but i also dont know how PUSH exactly works; Does it only "Push" when a change is made? or is it constantly updating like a faster "fetch"?

Can you guys share your "Mail, Contacts and Calendar" Settings, what your volume (quantity) of email and notifications is, your "Notification"settings, and your average use scenario is? especially if you have any tips on how to balance being connected, and maintaining decent battery life, or if you have any super-power-saving settings etc. What works best for you?