There are two ways a new GC might be helpful. It might reduce the length of any individual pause (though normally at the expense of total overall pauses) and it might reduce total memory usage by compacting the heap and being a precise rather than a conservative collector.

The current emacs GC can introduce long pauses, so I’d be happy to see something which improved Thant, and I have seen annoying increased memory usage in long emacs processes so experiments in this area would be welcome.