vlad gives 15% boost on damage from base stats.
The vlad upgrades do not.
Also since the lifesteals are nerfed badly and nobody even gets lifesteal these days.
I think giving 15% boosts on damge is a good idea on all vlad upgrade.
THe funniest part is that oct cores give more lifesteal than vlad LOL.
On "certain" heros I keep vlad till the end for the 15% boost which is a lot honestly.