The A string does not belong in the middle. There should be no middle. It's just wrong.
Haha, I generally agree with that - but there is no law against alternative tunings: my 5er has had various tunings over the years and I have now settled for D-G-C-F-A#. Weirdly comfortable for me, but only suits certain (usually dark, sombre) music. Clearly, I am living on the edge...