Well, rather late. However, I would like to share my ideas, most of them already shared by others:
I am working with the advantage since 10 years now, at work and at home, seldomly even exceeding 100 hrs a week. So I guess I have some experience with that keyboard.
I like the ergonomics, the curvature, distance between left and right dents, the key caps, location and splitting of arrow keys and and the overall appearance and size; not much to be done here. Curvature may even be a bit more pronounced for my taste.
My dearest suggestion: please, do (additionally!) implement Bluetooth. I am increasingly working with my tablet and mobile phone and I would really like to use my kinesis advantage if there are larger texts to be typed. This happens from time to time and it is getting more, although it is still far less than keyboard usage with my PC.
Please do not use rubber for the function keys anymore. If there is a space issue for real function keys, maybe they can surround somehow the dents (F7, F8 besides 5, T) or seldomly used keys like print, scroll lock, pause, keypad and program may be located elsewhere.
I really would fancy to have some kind of pointing device included. Whether this is a touchpad, a track point, a track ball or a roll bar, I have no idea of best implementation and location and leave that to you ergonomic-experts. I personally fancy the idea of having a track point for the right index finger between J and Y, automatically rendering the left-hand home-row keys to mouse buttons when the track point is touched. Well, considering licensing this will remain rather farfetched.
I would like to have further keys for mode switching, e.g. for alternative layouts like NEO. Possibly below both shift keys. There seems to be enough space and that location seems quite reachable by the pinkie. I would love to have additional keys above space and backspace, respectively, to a total of 2*7 thumb-keys in total.
I hardly bottom out anymore, but during start, the keyboard was considerably louder than my old one. Is there any way to add some dampers? I read about work around like O-rings, but it does not seem to complex to include something factory-wise.
The controller may use some updating. I would fancy more/larger macros and especially quicker macro responsiveness.
And now some nice to haves, which are not really urgent:
-No grooves surrounding the function keys. They are a pain to clean.
-Exchange of profiles. I have 3 advantages; it is quite laborious to keep them with identical configurations.
-An easily accessible SD-slot at the keyboard might be nice. I hate crawling behind a screen to search for the slot there.
-Switching of left- and right-hand side via foot switch. I often work using my left hand for the keyboard and the right hand for the mouse. If a right-hand key is needed, it is a bit annoying moving the mouse hand to the keyboard. This could be prevented by triggering that key via the left hand after electronically switching sides.
-Connecting foot switch via socket rather than via breakout cable.
-Option to purchase the keyboard directly with unlabelled key caps, more color options.