Commenting on your layout ...
Maybe I've got symmetry on the brain but I like having Enter-Delete-Enter in the bottom center between the two space bars, then Ctrl, alt shift beyond the spacebar. I'm finding that being able to hit return is very convenient from either hand while doing some shortcut key combination
I'd have the function keys along the top in a row as is traditionally done
Hmm, I see what you did, you added an extra two columns in the center to five you a big arrow block, but now that takes away from the traditional seven column per hand layout. Well, I guess I'd rather stick with the typical layout, take a look at this
(Attachment Link) 37389[/ATTACH]
Then use the other keys for whatever else you want, but I'd drop the old hangout PrintScr etc
Edit: Doh, forgot the return key, put it somewhere in the middle and shift around.
With 4 space bar positions you've taken the number of keys down to 102, which isn't so bad, but could cause compatibility problems. I settled on 103 keys because I have never seen a shortcut key that requires the use of the right windows key (that cannot be done by the left windows key). So, the traditional 104 keys minus right windows key seems about right to me. Also, I didn't want to have the space bar occupied by both thumbs - I think that one thumb is enough. The left thumb, in my opinion, can be put to better use.
I think that placing the space bar anywhere but on the bottom row is a mistake. It will be difficult for the thumb to reach over the bottom row, unless you are leaving those keys unassigned, in which case you're down to 100 keys.
In my experience, placing the space bar directly underneath the home position for the index finger results in an unnatural hand posture, as the thumb will need to slightly tuck itself under the hand to reach the spacebar. Your placement of the left and right arrows seems to force the thumb to rest in this posture. The reason why in my layout I have double keys for the left shift and space bar is to avoid this unnatural posture. For my hands, the natural resting position of the thumb, with my fingers on the home row, is somewhere between the key on the bottom row that's under the index finger, and the key to the inside of that one. Initially I tried a single key for space, but found that neither single key position felt natural, so I made it a double key and it feels much better now.
Also, maybe I'm not reading your layout correctly, but I don't see a shift key anywhere... Maybe it's in its traditional location? That's obviously a safe choice, but I wanted to experiment with a more creative solution in my layout. I wanted to put the shift key on the left thumb to avoid finger conflicts.
Consider, for example, the acronym ASAP. Which shift key should be held down when typing that? If it's the left, then the left ring finger will need to slide over to cover the keys that are usually typed by the left pinky (A), then the middle finger types the S, since the ring finger is occupied with the A, resulting in inconsistent fingering, and a hand movement away from the home position. The same happens when ASAP is typed with the right shift, since the P is usually pressed by the right pinky finger. The other option - switching shift keys mid acronym - seems inconvenient. This kind of problem, caused by a finger that normally covers character keys being occupied by a modifier, can be overcome by dedicating one finger to only modifiers - in my layout the left thumb. It makes for much more consistent typing, and less hand movement.
I see the elimination of the seventh column as a big advantage of my layout. I wanted to avoid those positions that require a hand movement away from the home position, and those seventh column keys definitely do that, especially the + key, which in a standard layout is absurdly far from the home position, though maybe not as absurdly far away as the backspace (8th column?).
So, it's not that your layout is bad. It's just that I have mostly the same complaints about your layout that I have with the standard layout.