Personally, I like mailing lists, because email is for me a very convenient way to centralize incoming messages/notices. I prefer notifications over polling, whenever the stream of notifications can be directly attributed/routed. Both, RT and possibly CPAN Forum have such a low-volume, but directly routed scheme - if somebody submits an RT ticket, or asks a question about my module, that is more or less directly a case for me to decide on, while Perlmonks has much "noise" that does not need my undivided or immediate attention.

That CPAN Forum is on the web makes it convenient for those seeking answers, but not necessarily for those providing these answers, as the questions are (hopefully) not frequent enough to make constant polling effective.