Hey,
I played a character based on INT/CHA during the beta, and it is completely playable.
In a 1v1 and smallscale pvp combat context, i found this stats really strong in the sense that currently the 2 most played and most efficient cc's (in my opinion) are stun and silence (power of..) based on CHA.
On the many duels done vs archers, melee build and others "mage" withe low CHA, silence + stun combo is gg for me, silence first to avoid purge then stun and you just pop your icespikes + any spell dmg (poison or corrosive spell, don't remember the name) combo it's done, i used blink spell + invisibility so i can reset fight, wait for cd's and re engage.
Even without the engage i have high resist on silence and stun with CHA & luck stats, and the charisma tree was not fully implement so maybe more stronger things to come, so yes definetly a stat to consider for pvp/gank.
My experience is based on duel with full stuff/enchant character on beta mostly, with all spell available so i don't know how hard it will be to build a character like this.
(sorry for my english, not my mother tongue)
