This is a rather side issue, but I'd better mention it:

Depends on your mail tools. I believe some do let you "unsubscribe" or "hide" a thread including future posts on it, or unsubscribe from a subthread (in the tree) while getting the rest of the tree.

With lists you get to tailor your reading with your choice of tools and scripts. With forums you don't, although tmo is quite well equipped, as they go, with tools of its own. But not, unfortunately, the ability to track replies, so it tends to discourage that style of communication and encourage a more "room full of people talking at once" style instead :-)