Interesting. In what way do you feel that the 308bits docking rings are less accurate?
The Bandai cones are slightly too rounded rather than having straight sides. It's almost like they're cross sectIons of a parabolic cone rather than a normal cone. They also have the TFA details in the flat central disc, which though based on the Original Trilogy details, are notably different. Especially the central pipes. The movie seemed to have straight pole-like struts in place of the four brackets where the cylinder meets the vertical sidewall (or no struts at all in some scenes - continuity error!), and the Bandai model has kind of incomplete triangles.
By contrast the 308bits docking rings seem just slightly too parallel, (i.e.: closer to a cylinder than a sliced cone) but it's subtle and at least they have straight sides. The flat central discs have a pretty faithful rendering of the OT detailing, complete with overhanging components. They are missing the raised sort of U-shaped pipes admittedly. The four corner brackets are unfortunately simple solid triangles rather than flat wedges with an open triangular gap, which is a shame as they would've been easy to print. The engraved panel lines are a bit too narrow and shallow compared to the rest of the Bandai moulding. In other words, they're closer to true scale, but too fine considering that they're going to be stuck onto an injection mounded plastic model with slightly oversized panel scribing! One annoyance is that the 3D printing process does result in aliased print lines. And because the part is mostly curved and cylindrical, these artefacts show up as scalloped lines. That is a by-product of the 3D printing machine, not the design, though.
In short, while the 308bits designs are not totally perfect, I think they're a much closer approximation of the Original Trilogy docking rings than the Bandai parts.