Well as thumb typing on this is going to be hard, you could say that is not an issue. But for those that want to not use it on a desk but in their hands thumb typing, an extra 1cm wide and keys close to the edges would certainly be an issue reaching for many. Edge to edge of keys are 134mm versus 153mm, so 14% wider key-section..., so a bit more than "two millimetres", it is "two centimetres".
...But I do agree that the extra few mm in thickness and portrait width is less of an issue, as Pro1 already is beyond one hand operation for the majority of people.