Our DM discussed the idea, but only to emphasize the "silliness" of all the new base classes. :-(
However, all the roles could be filled, one way or another.
TANK: The knight wins this hands down, but samurai also are good tanks also.
MELEE: Beyond the above, the swashbuckler is a descent fighter and the and hexblade duskblade makes a good secondary fighter.
NUKE: Warmage, Warlock, and Wu Jen all can nuke with the best of them. The former two are specialists on nuking, IMHO.
HEALING: The Favored Soul, Shugenja, Spirit Shaman, Archivist and Dragon Shaman can all heal, but unless your willing to devote a lot of spell slots to it (in the former four) or have a very finite pool of healing (dragon shaman) no one will be able to cure conditions like a cleric can.
OTHER MAGIC: Favored Souls, Shugenjas, and Archivists can all learn misc. cleric spells. Beguilers are great at deception magic, and dread necromancers can handle the role of summoner/cannon-fodder master. However, no one has access to many of the classic staple spells (teleport, invisibility, knock) so problem-solving via spellcasting is limited.
TRAPS/Stealth: Ninjas, Spellthieves, and Scouts all have Trapfinding. All but Scout have open lock. All of them have good stealth skills as well. However, each are more limited than a rogue when it comes to sneak attacks.
BUFFING/SUPPORT: Marshals and Dragon Shaman are great buffers, as is a properly laid out divine caster (but that does take from his healing, above).
"Best Build" For sheer versatility, my choice would be for a party:
TANK: Knight (hp, defense, good attack)
NUKER: Warmage (lots of attack magic)
HEALER: Favored Soul (lots of spell slots, a few additional non-healing)
TRAPS: Scout (stealth, traps, wilderness survival)
BUFFER: Dragon Shaman (aura buffs, additional combat, additional healing)