To preface, I am not talking about difficulty, or challenge or setting up a composition, I am going to miss 10 man raiding because it feels more personal with the people you raid with. I know all nine other people in my raid, we are all friends and do things outside of raiding together. Its going to be weird swelling a roster with 10 new faces, (Well you know what I mean) less time for inside jokes and the like, at least in the beginning.
I don't mind swapping to 20 man for any technical reasons, or raid performance or anything like that. I just like smaller groups (And no, not five mans; they are nowhere near the same thing) The only "technical" thing I won't like is my raid frames taking up more of my UI with more people :P
Anyone else of the same mind on this? Its kind of strange to try to type out why, I just greatly prefer raiding with ten people.