This is a cool move, and I hope it works out well. What does bother me is a seeming commitment to move away from the C codebase despite the fact that the funding/planning situation appears not to be ideal.
Arti 1.2.0: Onion service support (not funded, timeframe TBD)
Arti 2.0.0: Feature parity with C tor as a client (not funded, timeframe TBD)
Arti ?.?.?: Relay support
While timeframe is tbd, from the currently funded and higher priority tasks, it will likely be 2023 before these tasks get any look in. I’m worried that 2-3 years of C tor being on a skeleton crew and everyone else plunging ahead on a replacement that doesn’t have parity, or even core features, budgeted or planned is not a good place to be.