How should I position my choir in the choir stand?

A reader asked me for my thoughts about how to physically arrange a choir when they're going to sing.  I think the best positioning will vary from choir to choir.

Back when I was a kid, church choirs usually positioned themselves in rows, something like this (where S stands for Soprano, A for Alto, and T for Tenor):

TTTTTTTTTTT
AAAAAAAAA
SSSSSSSSSSS

But as time went on, more and more choirs started using a block formation, like so:

SSSS  TTT  AAAA
SSSS  TTT  AAAA
SSSS  TTT  AAAA

Sometimes the sopranos will be on the left, sometimes on the right.  Usually the tenors and/or basses are in the center.

I use the block formation and I like it for a few reasons:

1. It makes it easy for the director to signal to different sections of the choir.  If I signal to my right, it's clear that I'm talking to the altos.
2. When all the singers in one section are close to each other, it can be helpful to those who sometimes forget their part.  They can hear the others around them all singing the same note and they're less likely to drift onto a different part.
3. I'm not an expert on sound tech stuff, but it appears to be easier for the sound people to adjust the microphone levels to balance out the different sections.

But the block formation can have some downsides as well:

1. I've heard some choir members say that they don't get the full experience of the music because they can only hear their own part, the other singers are too far away.
2. On songs where the different sections are singing different lines and rhythms, it can be a challenge to stay on time together if sopranos can't hear the altos.

For those reasons, some choirs might do better with a formation where the different parts have more proximity to each other.

So a director will want to know their choir and choose the best positions based on their own choir's strengths and weaknesses.  A really sophisticated approach would be to try different positionings for different songs, but I have not done very much of that myself (there was one song, though, where the basses worked out a new positioning for themselves because they found that it helped them support each other for their difficult part).

Another thing to consider is where to put individual singers within their sections.  The singer with the loudest voice might need to be in the back, off to the side, away from the microphone.  And the one who forgets their notes sometimes can benefit from being beside the person who's always solid on the part.

When you have a really strong choir, you can do some beautiful things with positioning.  Like the choir I saw in Long Beach, the Master's College Chorale.  I wrote about it here -- http://the-church-choir.blogspot.com/2013/05/i-love-singing-with-you-but-can-i-still.html

What positionings has your choir used?  Leave a comment and tell me your experiences.