I agree with phat and TomD. The label is just a marketing thing, and aid to be able to categorize the footwear. I've seen boots advertised as for use with day hiking or lightweight hiking that you could probably wear while carrying a 70 lb pack amongst other weird things.

Anyway, I wear more traditional boots (typically made of synthetics) just because that is what I have found to be most comfortable thus far. I have experimented with trail runners and other varitions that probably fall between trail runners and boots with varying degress of success. So my advice would be to find what fits best and go from there. On a side note, the trail runners that didn't work out for backpacking made nice day hiking shoes that I use regulary during my training.