...not if you use vi style editing mode - which is awesome! :)

https://wiki.archlinux.org/index.php/readline#Editing_mode

It works pretty well if you bind C-a to send C-a. It is easy to get used to pressing C-a twice for beginning of line, and if you do it outside tmux it is harmless.

As someone who use intensively Tmux, I find easier to not touch the default configuration. Press twice vs use something that works perfectly.

You are quite lucky, C-a could easily have been the default and then you would have to either use it or have a config ;-).

The disadvantage of C-b is that you need two hands to press it on a QWERTY keyboard, so I kind of wish I had picked C-x or something instead. But there is no consensus about what the default should be (lots of people use C-a, C-b, `, C-e, etc) so it is not worth changing now.

With C-b you have less movement, C-a moves your hand in a weird form which creates pain in the hand. Apart from that, I use only my left hand to press C-b.

C-a is the default one in Screen but as far as I remember C-b is the default one in Tmux since the beginning of the project.

C-x is a bad idea too, because is another shortcut in bash (C-x + e bring up the $EDITOR). I think C-b is a good choice.

The only thing I change in tmux is the pane and windows number (I prefer to start in 1 instead of 0 because I can type with less movement).