I think so too.
Tanks seem rather useless.
I have seen everyone just run through monsters and bosses alike at lvl200+ with or without tank.
The enemies won’t even hit you anyway. The only time someone will ever hit you in this game, as it seems atm, is during Boss fights when you accidentally run into one of the invisible traps that the bosses at higher levels spawn (which they hopefully are going to remove in exchange for something like a unique enrage-mode for each boss).
And in that scenario a tank won’t save you either. A healer on the other hand can.
You could of course use a Centurion formation, but what for? I imagine it being much more time-costly to farm with a Centurion rather than just taking a cleric-type or another DD into your party to speed up the farming.
Centurion seems well-suited for botting though…
A party formation I could see myself seeking is: Barbarian/Doppelsöldner+Krivis/Paladin+Schwarzer Reiter
Massive buffs from steroids + Krivis buffs and then you just bash away with your AoEs at enemy mobs. And if you ever run out of mana, who cares? The 2 DPS classes can still bash the mobs away like nothing with their AAs while the Krivis mainly keeps the buffs up.