My situation:

I always use two cameras when doing documentary work. Yes it's a helluva lot of stuff to carry around - especially when you're stuck in a jungle or something - but it's also very helpful if one of your cameras break or is stolen. And that sort of thing will always happen when you least expect it.

I've been using a Sony Z1 HDV and Canon T3i DSLR the past 6 months. Each one has a particular function. The Z1 is fairly effective for 'run and gun,' shooting, for when I'm runnnig around shooting handheld stuff. Which is a lot of the time.

But the DSLR lets me use an assortment of lenses, is compact, and looks amazing. i use the T3i for most of my interviews (with a 50mm lens) and i also use it for super telphoto stuff - i have a 100-400mm lens.

From a traditional cinema-style point of view, a DSLR gives the DOP a wider range of lens options, wider depth of field, and lower light capability. Similar to shooting motion picture film. Generally more time consuming and preplanned. Whereas the HMC 150 is more for quickly capturing something - like an event.

So if the short fiction film involved running around a desert and has a 'doc-fee' perhaps the 150 is the better way to go. Otherwise I'd say a 600D is the better choice for drama.

At least that's what my experiences have led me to believe.