..., it doesn't matter that it is not on a part of the harness that is not designed to support bodyweight. So the legloop, because it is the lowest part of the harness, is the most effective place to place an autoblock. ...

A belay device stops the rope from feeding through by the friction created by the bend in the rope going over the device. A sharper bend creates more friction. All an auto block does is to create an acute angle in the bend, locking the belay device. Therefore the lower the autoblock is, the better. Also, because the autoblock is not actually supporting your weight, it doesn't matter that it is not on a part of the harness that is not designed to support bodyweight. So the legloop, because it is the lowest part of the harness, is the most effective place to place an autoblock.

I don't extend out my rap device. I don't like it so I am probably the wrong person to answer the second part of your question. However, I personally like to keep as few things on my belay loop as possible.

Wait.

You're saying that the leg loop is not load bearing?

I think you need to re-check your harness, mister.

I see a problem with using the leg loop to tie in your back up. If you screw up setting up your belay device when rapelling (i.e. not clipping the ropes with the locking biner), you can end up hanging upside down in your harness. The leg loop is much lower on your body's centre of gravity so you will naturally hand upside down. You might even smack the back of your head on the rock when you invert.

Check out this video from Sterling: http://www.youtube.com/watch?v=gYbWPbnFCQs

This is my favorite way to set up a rappel backup, although I use an autoblock and a regular sling rather than one of those PAS/POS things.

Let's be honest and admit that a lot (most?) people don't back up their rappels most of the time. To consider the backup a contingency against falling in case of rappel device failure -- which would then argue where the backup should be situated, as you have done -- is adding a function to it I don't think is appropriate. If you have the time to rig a backup, you certainly have the time to check and re-check the threading through your rappel device; an important habit to ingrain from the beginning stages of climbing.

"Department of redundency department. How can we help?"

I like your thoughts on ingraining the correct methods (rappel or wathever else) right at the beginning for newbies.

Personally, i always use a backup. Just because you check and re-check your system isn't a garantee you didn't frakc something up. You may as well use the best backup method you know and are confortable with. For me, it's the extended belay on my cow tail with a prussik below it and tied to my belay loop.

Fair enough. My thoughts are if we go down that road (e.g. using the prussic for safeguarding against not setting up the rappel correctly 100% of the time), then we should probably backup our belays too.

Let's be honest and admit that a lot (most?) people don't back up their rappels most of the time. To consider the backup a contingency against falling in case of rappel device failure -- which would then argue where the backup should be situated, as you have done -- is adding a function to it I don't think is appropriate. If you have the time to rig a backup, you certainly have the time to check and re-check the threading through your rappel device; an important habit to ingrain from the beginning stages of climbing.

I back up my rap every time UNLESS there is agood reason it might be unsafe. if i'm first down i have it on, if i'm second and i get a firemans i may leave it off, but even that is rare and only in certain cases. why on the leg loop? well it's convenient and that way the backup is controlled with my brake hand, i generally don't extend the device as i've had it hang up over edges ect, so that's situational, I just spent some time hanging from a tree on my yard fine tuning the length of my backup loop, could it hit the device and fail, sure, but i'd have to be bent in half at that point.
With rappelling a little paranoia is healthy imo.

Diff'rent strokes. I can see the point of backing it up every time, just like wearing a helmet every time. My disagreement is not whether to back up your rappel, it's why you back up your rappel. As you stated, there are also situational reasons, pro and con. I think the point is to decide your level of comfort, the protocol you wish to follow, etc.. and, like you said, to test out these options before you are out there.

BTW, I've had a situation with a firemen's I'm not sure was completely safe (in fact, it may have been very dangerous). I'd get into it more, but it would take a while to explain. I'll just say, getting a firemen's belay while cleaning your gear on rap may have some drawbacks.

if i'm cleaning something on rap i wouldn't rely on anyone else to hold me, in that case my own device and backup are what i'm relying on, i've even tied off my atc at times(with the backup still on) where i was attending to something. firemans' sketch me out, even with someone i know knows what they are doing.

I've seen some people that start with the ropes about chest height with a death grip on them just in case and by the time the rap is half done they are crouching over because of rope stretch...what are they going to do if i loose control? dig a hole in the ground and hop in to pull the ropes?

if i'm cleaning something on rap i wouldn't rely on anyone else to hold me, in that case my own device and backup are what i'm relying on, i've even tied off my atc at times(with the backup still on) where i was attending to something. firemans' sketch me out, even with someone i know knows what they are doing. I've seen some people that start with the ropes about chest height with a death grip on the m just in case and by the time the rap is half done they are crouching over because of rope stretch...what are they going to do? if i loose control? dig a hole in the ground and hop in to pull the ropes?