I would like to use external mic for interviews in small-medium size rooms, for the documentary. I don’t want to use a handheld mic, but rather a boom or similar setup and would like to avoid echo that is common in rooms. I've read a recommendation for Rode NT3 studio mic (http://www.pana3ccduser.com/article.php?filename=Using-the-Rode-NT3-Studio-Microphone-with-Panasoni)
(http://www.rode.com.au/NewBrochurePDFs/NT3.pdf) and several very good reviews about it.
Since this mic is hyper and not supercardioid, I wonder if it is a proper mic to use for interviews?
Thanks!

The NT3 is a nice mic for interviews, especially on a boom. For the price range - you'll get some nice rich sound.

It might be more effective to use dynamic lavs if:
- the room is really reflective
- the interviewee likes to move around alot
- or is uncomfortable with the boom mic

otherwise, I try to use the NT3 over the lavs when possible.

The NT-3 is a very good mic, however there are a few points to keep in mind in this situation. First it's a very heavy mic so even on a static boom it can be a problem. It may require a more sturdy stand, less boom length and additional sandbags in order to be stable.
Second, in a room with problem echo, a good lav placed properly on the subject will almost always pick up less of the room character. This will be something you'll need to listen to closely and determine if you're getting satisfactory results while there's still time to do something about it.