I use Mirinae (the smite gem) instead of toxin, seems to work out better for me at the moment. The crits on smite are generally 35m so I get a lot of single target dps out. I haven't checked to see if wreath can proc smite like it does toxin though. But I guess my build focuses more on straight frenzy damage with furious charge for mobility / cc, so it might not work as well with WW.
http://us.battle.net/d3/en/profile/Apoc-1110/hero/51835243