I've been thinking about this "slam-thing."
In the old Hammer films dominated by Peter "Grand Moff Tarkin" Cushing and Christopher "Saruman" "Darth Tyranus' Lee, Dracula used to lift, throw, wrassle, and otherwise physically abuse his foes.
In Copolla's Brams Stoker's Dracula, Dracula slaps the TAR out of Quincy and someone else (can't remember). He also repeatedly slams Renfield into metal bars.
In the old Bela Lugosi Dracula, he strangles Renfield.
In the Frank Langella Dracula, he flings every around like rag dolls and effortlessly kills Van Helsing at the end (indirectly leading to his own death).
Now, granted, these are movies but these are also examples of the most "classic" of Vampires. In all of these examples, Dracula is flinging, throwing, slaming, smashing (he smashes from a heavy wooden coffin in one), and otherwise physically abusing mortals and lesser Vampires.
We've already noted as well that in your more "folklorish" stories, Vampires seem to suck the strength out of victims they touch or are physically close to before biting. And, in Anne Rice's stuff, there are many times when victims seem to be stunned before they are attacked (although as mmadsen suggested, this could also be a version of the dominate power).
With these examples in mind, I don't see a problem with the ability based upon classic, folk lorish, and "modern" concepts of Vampires.