On the one hand, I can see a certain symmetry to the roles each being associated with one of the bending styles.
On the other hand, I could see arguments for some bending styles fitting multiple roles. For example, waterbenders could be either leaders (healers), strikers (icicle missile attacks), controllers (tidal waves), and so on.
Avatar has two primary power sources - martial and elemental. You have to account not only for the cool benders, but also for characters such as Sokka, Mai, Ty Lee, Suki, and so on. Plus, some of the benders have cool fighting skills as well, such as Zuko.
For elemental characters, I can see the following:
Airbender - Striker (quick, makes individual attacks typically)
Earthbender - Defender (Unmovable as boulders)
Firebender - Controller (Can attack many enemies at once)
Waterbender - Leader (Includes some healing powers as a buff, but can hold their own)
For martial:
Fighter - Defender (i.e. Sokka, Jet)
Monk - Striker (i.e. Ty Lee)
Rogue (Assassin?) - Striker (i.e. Mai)
Warlord - Leader (???)
??? - Controller
Anyway, those are some random thoughts. I think Avatar would work nicely with 4e, perhaps better so than in 3e. Whatever the case, I hope somebody puts this together.
