Tier 1 (which grants +2 damage): 14 Cha
Tier 2 (which grants +4 damage): 16 Cha
Tier 3 (which grants +6 damage): 18 Cha
Tier 4 (which grants +8 damage): 20 Cha.
Comparing these values with the U19 version shows that the new version makes it harder to get the same bonus as with the old version:
I'll illustrate this with an example, my 18Pal/2Mnk TWF Paladin: He needs a base charisma of 18 to qualify for Divine Might 3, i.e. a bonus of +6. In order to get the same bonus from the U19 feat, he needs 12 more points of Str, i.e. a Charisma of 34, which means that you'd need to get (in comparison to the 18 base with tomes) +16 Charisma from items and enhancements.
The numbers are a bit different for non-monk TWF and THF pallies, but it's still the same trend: You're going to need a grave investment in regards to tomes, items and enhancements to increas your Charisma to a value which is close to a level 5, 10, 15 or 20 (U18) enhancement.
I see the benefit of a bonus which scales and the versatility of a bonus to str, but this is a downsizing of the ability and makes things harder for high-Cha-paladins who fight with dynastic falcatas or Epic Elyd Edges.