While I said I would play this class before certain others, my gut feeling is that because of those "ally only" mechanics, the vampire class won't play the same in every group. For example, I don't see good odds of other players in my group letting a vamp feed on their PCs.
You know, I was re-reading the vampire from a combination of this thread and watching Dyland Dog with my wife, and realized something I missed. I may also be misinterpreting the rules since I am not looking at them now, so if anyone corrects me I will edit my post to reflect it and give them cred for it.
You probably can have a perfectly viable experience without using your buds' healing surges.
So long as you have 1 additional healing surge above your default at your short rest, you get all your HP back.
So, assuming you do not need to spend a surge during combat, using blood drinking once gets you full HP. Even if you spend a single surge, using blood drinking once, and then another on a disabled prisoner after, gets you up to full HP.
Multiple uses of blood drinking further enable this, meaning that you could spend four surges in combat with two uses of blood drinking, and only need three prisoners and 15 minutes to get back to full health.
Which, of course, runs the risk of your vampire ending up coming across as a very very bad man, and thus maybe not welcome in the group to begin with, which actually enforces your point.