I noticed above that you seemed a little concerned that, by discarding the milestone system already part of the core
4e rules, your players might end up with fewer action points than they might otherwise have gotten.
I think the oWoD system you describe is a fine way to get a few more points flowing; HEX handles things in largely the same way, but relabels the idea as "Motivations and Flaws." Mutants and Masterminds does much the same, but lumps all those disparate ideas into "Complications."
One thing you might also consider stealing from M&M is the "Haha I totally screwed you over" action point. If you need to fudge the dice on behalf of a foe, trap, or other situation (and against the PCs), reward them with action point for the trouble. This removes some of the guilt when you're trying to keep the main bad guy in a finale alive (for example), and gives the players some motivation to "play along," if necessary. It's one of the single most elegant "narrative control" elements in M&M, and one that I don't think would seriously unbalance
4e in any way.
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