reddit is an echo chamber even worse than here. i dread depending on its platform for any content
The tone of reddit is set more by downvoting rather than upvoting. Any post on proggit about any language people actually use gets voted down by an army of bots written in languages that people don't use. Also, they're a bunch of communists because they'll vote you down if you drop any hint that (1) you're in it for the money or (2) you care about business in any way.
Reddit's negativity might make it spam resistant, but it will repell mainstream audiences and prevent their expansion.
The sort of political and organizing power reddit has shown recently (say, with the SOPA campaign) is not thinkable on facebook or google+. An AMA on reddit has also become a required stop for actors/directors/authors etc. for promoting their latest projects. G+ can only dream of such reach and power and facebook is by design (and branding) not suitable for such "interactive-broadcasting" type of usage.
now, if you want to start to discuss effectivenes instead of size, take a look at slashcode voting system.