On this page: http://www.cohplanner.com/
The link under this text: Log In
Goes to: http://www.cohplanner.com/login
Which sends the user to a "sorry, we're down" page with this text:
Sorry, for the inconvenience. SuckerPunches' Issue 9-compliant Planner has been brought offline for the time being.
Should it instead send users to: http://planner.cohtitan.com/planner
Eh, I didn't want to say anything, I think we were all waiting for SP to chime in lol.
The legacy and new online planner are not backwards compatible... and also keep in mind that they are both completely different, at least in code-structure... meaning making them backwards compatible would be tasking... and in the end, probably not worth the effort.
Also, there have been a slew of "unexplainable" database issues that have been coming from the legacy script, so the [intelligent] decided solution was to disable the legacy and more or less point the users in the direction of the new one, that is actually for more recent is game-data.
I'll wait for the other two active admins to chime in if they feel my explanation is less than accurate... but I think that pretty much covers the legacy online planner.
The new one is a feat in it's own; albeit still a little buggy thanks to modern-browser differentials in what they think is a supported standard respectively. (For example, IE doesn't support HTML5 where as most other modern browsers do, at least in part) So what works great in one browser breaks in another... causing most of the notable UI issues on the new planner.
It will be awhile before any of the active developers have a chance to update the current online planner, unless the creator (SuckerPunch here) makes another comeback tour...