Most of the people I introduce to Slack and may in future introduce to Ryver find the Enter = Send default very disconcerting. It's one of the first experiences they have and it's often negative ("But I haven't finished what I was trying to say!")
It makes sense in a quick-fire chat situation, but not when people are posting considered responses that need paragraph breaks (or bullet points). Any chance of making it a user-selectable option whether Enter or Ctrl+Enter sends a message? That simple change would improve the UX greatly for many people.
Customer support service by UserEcho