Not quite. If you want to append or insert characters using blockwise visual mode in vim, it won't work with Ctrl-C. It will work with Ctrl-[ or Esc.
That's true for the default behaviour. Ctrl-C also won't call autocommands (like InsertLeave).
But - you can always map <C-c> to <ESC>, so that it'll work exactly the same.
I both knew this and read the post I was responding to, which also brings this up as an option. I commented about Ctrl-[ because it was the last previously-unmentioned option.
My bad. I didn't even catch that "ctrl-c" was mentioned in the parent!