I think the survival bots are a bit too strong for survival, especially because they don't lose any cards from their deck over time. One of the biggest reasons I stayed out of the manual brackets, even though I wanted to play in them, is that I didn't think there would be enough players enrolled to get consistent human vs. human battles. If I'm going to end up playing against a bot, I might as well do it in the bracket with the highest CP and best rewards.