I purchased the Montrail Masai because I read that it was equally good on streets and trails. I was training for a street marathon by running about 50/50 street and trail so this was important to me. After training and running a marathon in these shoes here is my take:
These shoes are a dream on trails. The stiffer sole and aggressive tread make this shoe ideal for running over rocky terrain. On top of that, they have excellent foot support. Also, I appreciated the mesh upper and ample toe room. However, while these shoes certainly perform adequately for street running, I would not recommend them for an entire marathon on pavement. Next time I think I'll try to find a shoe with a little more give in the heel to soak up the relentless pounding of street running.