I honestly do not see the advantage of wasting a key in order to obtain a larger space key. Esthetics? Looking more like a Pandora? Ergonomics or functionality are certainly not an argument: whether the key is one or two units wide, it is still only within reach of the right thumb and the way to find it will still be "hit the penultimate key on the bottom row", not "find a larger-than-usual key somewhere and press it". On the very first use the visual clue of a larger space key could make a tiny difference in the learning curve, but I think that is a negligible difference compared to all the other things you'll have to get used to anyway. Yes, maybe you win 2 seconds trying to find space on your very first use. You'll lose much more time in the end by having to live with one less key. The disadvantages of a double-wide space key are clear: one key is wasted (if you think that is a small price, then please tell me which key you would like to lose. Shift? Tab?) and it becomes impossible to map some keyboard layouts. Also, consider the scenario where there would (eventually) be two versions of the keymat, one with a single-width space key and one with a double-width space key. Then if we have a case which fits the single-width keymat, then to make it work with the other keymat, you just have to manually remove the separator (presumably with a cutter knife and some time it would be possible to do that relatively cleanly). If the case fits the double-width keymat, then you have to manually create a separator, which is impossible to do in a clean way.