I understand your point. I like Wizards but I wanted to avoid them in my current party. So I took Druid and Cipher for CC, and for now it works. (Well, I would be perfect when the storm bug will be corrected. ^^)
But currently, I doubt chanters can replace Priest, even with druid and paladin.
Part of the problem is you can't really go "full Buff bot" for chanter ; indeed, you can't customize so much a chanter.
By the way, even if chanters had around 50% buff capabilities of Priest, it would be ok.
You could indeed rely on druids, paladins and paladin multiclass talent to fill most of the gap, and your party would have other abilities to compensate anyway (especially chanters and pally tankyness).
Now I would estimate chanters around 25-30% of priest buff capabilities.
The gap is still huge is you consider for example priests can get up to +65 party deflection, while chanters cap at +10 with a 3rd level chant.
The Chanter gets it done by debuffing the enemy, which ends up being the same as buffing yourself. He doesn't heal but he's the best off tank in the game. I adore the Chanter, truly in love with the class as it replaces the traditional cleric role in a completely new way. The Chanter really is the alternative to Priest since you probably don't want both of them in same party unless you looking for a very funky party mix (pure defensive or no-tank).