Vanguard on Ranged Heroes

So what's the consensus of buying Vanguard on ranged heroes? I've been told it's not a very good pick-up on ranged heroes considering the reduced damage block. However, I do see people recommend it on Razor / Viper / Batrider / Weaver alot, so I'm confused as to whether it's a viable pick-up. Is the regen + health worth the reduced damage block in those cases?