In my opinion, having str or dex heroes using int based skills is only viable for low level buffs i.e. Oath of Desecration, Absorb the Elements, Become Air, but low int will sometimes make these skills fail to be cast when used.
For me I find it worth the risk though, I'm currently playing a scoundrel (dex hero) on hard difficulty and I use skills like:
Oath of Desecration - Witchcraft (int)
Rage - Man-at-Arms (str)
Melee Power Stance - Man-at-Arms (str)
Tactical Retreat - Expert Marksman (dex)
So when I have an opponent knocked down and have the effects of Bully, Oath of Desecration, Rage, Melee Power Stance, and Backstab, I do damage like the following:
https://www.youtube.com/watch?v=qpAMpSCEgQ0 
