Role Manager plugin with v. 2.1

Has anyone got a sense of the compatibility of the Role manager plugin (https://redalt.com/wiki/Role+Manager) with WordPress 2.1?

Having installed 2.1 on a test site, I see a couple of quirks with Role Manager, but it does seem to function at least partially.

The Role Manager admin page now displays awkwardly as one column of roles going down the page rather than three columns as before, but after a quick check of a couple of minor changes it seems to still function.

But I’m nervous about upgrading my primary sites, as role manager is a pretty complex and, for me, important plugin.

Any others gone down this road and discovered other problems.