Coming back to this topic since the guys bumped it.
I was playing a lot with my clan doing rifts, but a number of them are taking a break to play the new WoW patch, so I've been playing public games. I highly recommend doing that for quicker gearing and higher paced playing than solo. I have not yet had a bad experience with anyone trying to deliberately mess things up. One thing that could be better is people taking a moment to see if they got any loot to trade after a rift, the focus seems to be on clearing the rift, closing it and starting another as quickly as possible.
I'm going to try doing greater rifts too, see how they work out with randoms.
Also, playing in a public group exposes you to lots of players who will be using similar or greatly different builds than you. You can see what other people are trying and often make friends this way.