I would expect the cooling to have a scaling advantage-- heat gain is proportional to surface area, but the mount of superconducting mojo you can use is proportional to volume so it should be more energy efficient to build larger devices.

The authors' power comparison is outlined in Section VI of their paper [0] (page 11-12). You might be able to figure out some intermediate scalings from that!

[0] - https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=929...