Agreed with @Lunderberg. Also to note that most of major features submitted to main are eventually and exclusively used in unity, for example, NCCL/RCCL integration in CMake system. As of now, developers usually have to submit two parallel PRs to both branches, or wait for another merge from main to unity to happen to actually use those features, which is quite inconvenient.
Therefore, the T1 solution, i.e. switching unity to main, will ultimately benefit development productivity and help us evolve with velocity.