I know a while ago user-2 said that after 2.91 was released, the Git HEAD would be divided into a development section and a maintenance section.

I get the impression from the mailing list that this has happened and there is a development branch but how do we get to it and should we update from it like we used to with Git HEAD updates? Did it get divided into a maintenance section too?

See "Development Version" in installation page in wiki. As to whether you should update from it, the answer is no. All the old "Git HEAD" shenanigans are no more. Installation and usage of the development version is completely unsupported, by me anyway. I plan to keep a development branch in case the small number of people who can make use of it might provide any useful feedback before the next release, but it's mainly for my benefit. I don't know if there will ever be maintenance branch per se. Any obsolete code in get_iplayer is not worth keeping around.

Thanks.
What happens though if the BBC break things again like they did last year? There were a lot of fixes put into the Git HEAD before a new full version was released and a number of us switched to the HEAD script while we were waiting for the official release.

The only difference is that now any new code is kept on the "develop" branch at GitHub rather than the "master" branch. I'm going to endeavour to avoid any repeats of the mess in Nov-Dec last year. That finally convinced me that updating from GitHub is not a supportable system. Part of the reason for splitting off a development branch is so that I can make make hotfixes for BBC-induced problems separate from mainline work.

When I said you shouldn't update to the development version, what I meant is that you shouldn't need to, but you should of course feel free to do so if you like. Nov-Dec was peculiar in that most programmes would download OK, but the BBC eventually destroyed access to programmes on a couple of channels, so if you wanted programmes from those channels you needed an update. As I said above, my goal is that nobody should ever actually need to do that again, at least not for very long.