Now that's a different and helpful perspective. I've never done any "wheel-spin" starts with the Roadster, although after the clonking had started (due to the detached ATB waggling up and down and hitting the floorboards) I did pull away sharpish from a junction and had felt a strange wallowy sensation. That would've been tramping I guess. I did have a look, and I'd say there's room beside the battery to install another ATB on the nearside.
Interestingly, you say "However one ATB, i.e. one on one side of the car, will unbalance the car quite a bit if you get any distortion in the springs whatsoever, as this will induce some level of rear steer effect coupled with a height difference between wheel and body either side of the car. I have always thought that the fitting of just one ATB was a ridiculous solution to spring damping by MMC".
In the car's history file, in Nov 2012 at 9K miles / 4 years old, a respected specialist dealer commented (after a service): "it was discovered that the rear offside is 1/2 inch lower than the nearside". I have always attributed a slight difference to spring sag, but I wonder if that's what this was all about.....
