I'd prefer Discourse, mostly for selfish reasons, but
also for the fact that others can continue to use it like the mailing
list should they prefer.
I'm not intimately familiar with it but as I understand it largely
offers the same features as the mailing list and more (allowing
interaction via email, a richer and more modern GUI for searching /
subscribing to specific topics, SSO for integration with Bitfolk's LDAP
etc.)
I have a significant dislike of email which seems to only get worse
with time, so if having discourse allows me to more easily interact
and keep track of current and previous discussions, but also more
selectively subscribe to certain topics (and opt out of those that are
of no interest - obviously important Bitfolk communications are always
of interest), then I'm all for it.
Cheers,
Luke T