Ah. That's interesting. Thank you for this helpful link! I'm not sure I'll do it here and now on a brand new device (that I wouldn't know how to re-flash if I break it), but if time passes without a proper plug-in in sight, I'll know what to do. The restrictions you mentioned I could live with.
A very different issue: In the accounts setup, I don't find a way to change username/password for existing accounts. (Google, flickr, SIP, mail accounts, all the same) I'm not gonna try now, but what will happen if I change the password for an account on the server? Will I have to delete and re-create the whole account or will the N9 ask again once a login fails?