Have anybody started using this in their layout yet?
I think the first thing we would need to see is are there any limitations to same-row chording (software or physical)?
Then we need to find out how long it takes to press/release 2 buttons in the same row. And compare it to press/release of 1 button and also press/release of 2 buttons in adjacent rows. We have people here who made tools to do this measurement, but the tools probably need to be adjusted to accommodate same-row chords.
If it's significantly faster to press 2 same-row buttons, TabSpace (and Backspice, which is based on it) and probably all other layouts will have to be completely re-thought.
For example, as 'THE' constitutes around 6.42% of all words, "t", "h" sad "e" buttons will need to be arranged differently, probably with "t" and "h" being on the same row next to each other.
Also several frequent letters that before required 2 buttons can now be moved to a one press of 2 buttons in the same-row.
I think we also need to come up with a better terminology for talking about "buttons in the same row next to each other".