@dlang posted on a chain take-up idea a few weeks back, which I thought had a nice alignment with this.
https://forums.maslowcnc.com/t/chain-take-up-idea/1999
His idea was to have a circular wheel to wrap the excess chain around, and use a stretchy-rope to create rotational tension to pull on the chain. I thought that idea supplemented this idea, because the disk for the stretchy-rope could be a slightly larger diameter than the disk for the chain; it could be larger by any fraction, so that the motion ratio was not restricted to fixed fractions, unlike the above solution. It could be just 10% bigger in diameter, such that the amount of stretchy-rope take-up was only 10% more than chain take-up. This compares to 50% with the above solution. I thought that the ability to tune the motion ratio to anything, not restricted to fixed ratios, would enable better calibration of the tension across the entire work-area.