Ralf Hildebrandt writes:
Where else do you expect to find this information, so we can put it there?
I must admin I haven't tried installing yet, mainly because I didn't know how to "go back" in case of problems.
Repeating what I already wrote for completeness here: Migrating and then going back all at once is not necessary. You can migrate bit by bit, although it may require a little bit of manual fiddling if you get to the point of installing both on a production server. By "little bit" I mean installing in {/usr,/var}/lib/mailman3 instead of {/usr,/var}/lib/mailman where Mailman 2 probably lives.
I have to admit I haven't installed into one of the standard hierarchies yet; I run my Mailman 3 lists (all test or non-mission-critical) out of a Python virtualenv in my home directory.
Re installing betas from source:
I wish I could say, "oh, just try it, you'll like it", but building from source isn't as automatic as I'd like. It's not a huge extra effort (ask here), and I have had it install (a few commits back) with just "bzr clone ...; python bootstrap.py". I just prefer a reliable, completely turnkey package when recommending to "pure" beta testers, and it's not quite that yet.
If you do try it, be warned that a couple of tests may infloop (for reasons unknown), although only under some circumstances.
Steve