As I posted in your other thread, by completely separating the means of inflation from yourself, you add another layer of risk. Most popping incidents in stories occur from rigid or spherical overinflation, where the victim is too inflated to move to shut off the helium tank or remove the hose from herself. With sympathetic inflation, if you float up to the ceiling, even if you can move perfectly well, you're still screwed. You can still try to get back down, though, which makes for a more interesting story than just waiting to pop.
Sympathetic inflation also raises the specter of permanence. What if the balloon reaches its limits before you do? Or you tie off the balloon and it floats out a window (ignoring that in the real world it would pop as the pressure dropped)?
*gasp* One of my stories is mentioned! Thanks Sven!
As for the topic, I like the "voodoo" style inflation, as it has potential for unwanted inflation, or out of control inflation. What would happen if your balloon got mixed up with another huge batch? There's also the slightly control aspect, which can be fun sometimes :)
No, I would not want to live in a world without dragons, as I would not want to live in a world without magic, for that is a world without mystery, and that is a world without faith.