Performance is basically the same (in microbenchmarks), they went as far as preserving the use of red black trees for an apples to apples comparison, but it’s going to improve security as binder runs inside every process.
That means binder is going to join Asahi graphics, the Android Bluetooth stack, and puzzlefs in the serious drivers written in Rust club.
Distros will work a bit at shipping the right toolchain the first time they ship a rust-written module, but otherwise, it can’t break userspace. I guess they’ll start by merging the close reimplementation to make regressions easy to track.