Can't say I care for the heroic portion of it.. wish it was as flexible as the normal -> heroic -> normal swapping as we have currently for ICC. Will kill a lot of the flexibility of the new system for those guilds that are currently working on heroic content only since you won't be able to swap to a 10 man version of the instance.
I know it will retain the current flexibility, but just not the same flexibility that normal mode will enjoy in 4.0.1+