Isn't one of pony's strengths, that it's doing GC better?

As a developer writing code, I don't particularly care whether GC is simple or complicate, as long as it works correctly. That's the compiler writer's job.

A fundamental strength of Erlang is that as many things as possible are simple, which makes it easy to know that it works correctly and under what conditions it doesn't work so well [1]. The compiler writer isn't necessarily the GC writer either; although, it's probably the same couple of people in Erlang.

[1] If you touch a lot of ref counted binaries, without generating enough garbage on the process heap to trigger GC. GC time scales with process heap, if you get a large enough backlog in your mailbox, GC may reduce the throughput to the point where you can't recover, although doing selective receives if you don't trigger the optimization for new references[2] is much more painful than GC scaling.

[2] http://erlang.org/pipermail/erlang-questions/2010-June/05175...

EDIT: from slides about r19 GC [3], it seems that both of the GC issues I mentioned have had targeted changes: for refcounted binary issues, there's now a 'virtual binary heap' to help trigger GC; for GC with a big mailbox, there are different allocation strategies available which may help.

[3] https://www.erlang-solutions.com/blog/erlang-19-0-garbage-co...