You guys seem not to understand what I meant before. Yes I know the Deathadder isn't designed for the ring finger to rest on the right MB. But that in combination with the wider front makes the mouse rotate counter-clock wise inside your hand... but I'll come to that later again.
The thing is (and not many people know this) that some mice are designed to keep your ring finger on the MB, like the Xai/Sensai or the Lachesis (although it has nothing to do with these examples being ambidextrous per se). Of course you can still put your ring finger on the right side of the mouse but not only will this feel uncomfortable after prolonged usage, but it will also produce the problem I mention with the DA above. It will automatically rotate the mouse counter-clock wise for a few degrees within your hand because the ring finger pushes against the front right side of the mouse and that of course also rotates the x- and y-axis, making your hand coordination needing to compensate for this behavior.
Interestingly I didn't use this grip myself in the beginning when I received a pre-release Xai. So I have to admit I didn't like it's shape that much because of the issues mentioned above but first of all it just didn't feel comfortable (so I didn't really use it after testing it for a while). Now it might have been a year later that I gave it another try and accidentally put my ring finger on the right MB. Now I reckon this felt awkward at first... awkward but WAY more comfortable. So I tried to stick to it for a while and realized that the shape of the Xai has to be one of the most comfortable and natural to my hand WHEN holding it the way I described before (ring finger next to the middle finger on the MB).
Now I know that the DA isn't designed to grip that way -- the right MB isn't wide enough and has this bulge at the edge. So yeah there's no other way with the DA other than to keep the ring finger on the side of the mouse -- and don't get me wrong it does feel really comfortable. Absolutely no issues with that. But this shows the problem I'm talking about without over-explaining this thing:

In the previous picture you could see the angle of the mouse how it is aligned in the hand and how it actually should be aligned (again: this is with the ring finger on the side how probably everybody is holding their DA and how it is comfortable). This rotation wouldn't happen if (Option A:) the right front side of the mouse wouldn't be as wide as they designed it to be, so the ring finger wouldn't be pushed out as far to the side. (Option B:) They could have also made the right MB a little wider but without that bulge (maybe even sloped down a little) just like the Xai/Sensei for example. Option B would make it optimal to put the ring finger on the MB next to the middle finger, so it would change the ergonomics quite a bit making it a bit of a hybrid of the Sensai and DA shape.
Anyway the rotation of the DA within the hand causes another problem (maybe not for everybody but at least for me): As you can see in the next picture that's how holding the DA looks from above -- no issue at first sign. But if you look closely there's a big distance between the index and middle finger and to keep it that way I have to force those finger apart a little. While this doesn't give an issue at first, after prolonged use it does feel a little uncomfortable because after all I still have to force those fingers in that position.

In the following image you can see how my index finger would rather rest naturally (without forcing it away from the middle finger). Now during usage my index finger never rests on the mousewheel as you can see here (as I actively keep it away of course) but I find myself often touching the side of the wheel. So not a BIG issue but after a while forcing the index finger out gets it tired a little, which is enough to show that the design isn't perfectly thought through.

OK just as a comparison here's my Lachesis (and it's no different to the Xai in that matter). In that picture I keep my ring finger on the right MB (actually to be more specific it's the side of the button where the bulge slopes down again).

Here you can see how I'm holding it from above (notice the more natural distance between the index and middle finger as opposed to the DA):

Now the following image is interesting in that it shows that the Lachesis (as an example) is a mouse that's not intended for gripping it with the ring finger on the side:

As you can obviously see the ring finger is pushing the side of the mouse in a way that rotates the mouse within the hand (although the interesting thing is that at least in my hand it's still less rotation than with the Deathadder). But there's one more thing specifically with the Lachesis (doesn't happen with the Xai/Sensai because there's not such a huge difference in width between the front and the back of the mouse). Notice that I have to curl my pinkie in order to have it set lower than the ring finger so I'm able to touch the side of the mouse with it. If I wouldn't do that and stretch the pinkie in a more natural position it would stay pretty much next to the ring finger. That means that the pink line (depicting the angle of the pinkie) would be more parallel to the light green line of the ring finger thus making less contact between the pinkie and the side of the mouse. I noticed it because it leads to less grip when lifting the mouse.
Also in comparison with the Deathadder there's not that problem of an unnaturally wide distance between the index and middle finger. Nope but the same thing happens now between ring finger and the middle finger, because as you can see the width of the front of the Lachesis is quite gigantic compared to other mice and as you keep the ring finger at the side it really pries them apart. And while with the Deathadder this gets uncomfortable after prolonged usage, with the Lachesis it's just horrible from the second you put it there.
So in essence: I know that was a pretty long explenation but all I'm trying to say is that the Deathadder in it's actual shape when gripping it the way it is (poorly) designed for, leads to rotation of the mouse in the hand which may also lead to a wider distance between the middle and index finger (tiring because unnatural). One way to solve this would be to put your ring finger next to your middle finger on the right MB. Unfortunately the right MB is not wide enough to keep both fingers resting on it without stuffing them together and you would also have to keep the ring finger on this bulge which is not that ergonomic either.
To eliminate these issues there'd be 2 ways to reshape the DA:
a.) Make the right side at the front and the button itself a few millimeters narrower. That way people could continue using the mouse with the ring finger on it's side but without that (excess) rotation issues.
b.) Make the right MB a little wider but ditch that bulge and shape it a little convex with a downward slope. That way it would be possible to keep the ring finger next to the middle finger on the right MB and therefore also eliminating the rotation issues.
Edited by MONVMENTVM - 11/8/12 at 5:05pm