For the Tilde vs Esc problem, you may have a look at my GuiFN layout:
http://geekhack.org/index.php?topic=57723.msg1313182#msg1313182
I believe there is actually no need for an additional key.
Thanks, I hadn't seen that yet.
It's interesting that you chose essentially the same position for the Tilde key.
Initially I was just going to do it like in SpaceFN, and as everybody else does, with Fn-Esc.
Then I realized that this Caps Lock key could find a much better use.
I have now retrofitted SpaceFN with the same trick (backquote/tilde on Caps Lock, Caps Lock done with Fn-CapsLock).
One thing that I would like to stress out is that the Esc key is a key that developers now use constantly. The culprit is autocompletion. In modern IDEs, when you start typing a few letters the IDE opens a list of all words and symbols that may correspond to these letters. You need to press Esc to close this list, or else one of the items in the list is going to be validated when you press space or any other punctuation symbol.
For example when typing C# code, just type the letter "i" and you already have a list of possible completions (basically any variable, class or method name that has a "i" in it). Most of the time in this case you will have to close the list by pressing Esc. It's not the only way, but it's important to note that you end up pressing Esc several times for each line of code you type.
For this reason, in SpaceFN and GuiFN I have now opted to NOT overload the Esc key. I mean that Fn-Esc does Esc. I got caught too many times pressing Esc while I was still holding the Fn key.
In your case, it would mean that you need to make Esc very accessible. Only your option 3 does that cleanly.
For the navigation cluster, I would recommend option A.
People who use their keyboard heavily for text editing need to do all kind of chords with Ctrl and Shift. Adding another key to chord with, just do to Home/End/PgUp/PgDn is a pain. It's a pain because there are already many chords with these keys (Ctrl-Home to go to the start of document, Ctrl-End for end of document, Shift-Home to select to start of line, and so on).
Good points. I'm currently siding with 3A, eventhough my personal favourite is 2A (which I fear is a little too strange).
Option 1 is clearly the worse. If you are going to have a narrow key, it's better to put it on the edge of the keyboard, because there is no key at its left to press accidentally.
I'm reluctant to mess with the Caps Lock key too much. I don't use it myself, but I know writers for whom it would be a dealbreaker, and coders who would remap it to Ctrl. Option 3 has it 1.25u wide, which should be wide enough to still feel normal.
Are you going to have DIP switches to configure a few options? In this case, just offer the ability to have either CapsLock or backquote directly accessible. I would guess that the set of people who want one option has a small intersection with the set of people who want the other one.
I don't really see people who need frequent access to CapsLock having also a need to access frequently the backquote/tilde.
Also, the position and shape of your left Fn key makes it very easy to press Fn-CapsLock, which mitigates a little bit the problem.
Cramming an additional key in there (and it's a narrow one) is not really elegant.
My plan is to make this a group buy that eventually becomes a product. The GB would include a PCB-without-switches option that supports both Nav cluster options A and B, for those with a strong preference.
We'll also be selling the keycaps that make this layout possible, so anybody who wants to do a more traditional 60% (or programmable version) can roll their own.
I think this could be a wildly popular option.
Do I read correctly that your keyboard's firmware will be programmable?
One last remark: I think that on your keyboard there is one key that would actually benefit from being narrower. It's the Del key. It's in an area that is going to see high traffic (right Shift and arrows are there), so making it slightly smaller would probably prevent a few disasters. And it would not really be much harder to reach, as it would be on the edge of the keyboard, and easy to locate by feel as it is above a void. It's actually located in a corner, so it doesn't hurt if it is smaller than the other keys.