Originally Posted by Blue Order
In terms of performance, it's not a matter of opinon. It's a matter of physics. A mountain bike simply cannot go the same distance as a road bike on one revolution of the pedals. Therefore, in order to go as fast as a roadie, the mountain bike has to pedal at a faster rate, just to keep up. If the "roadie" and the mtb are in the same physical condition, the roadie will leave the mtb in the dust, every single time.
Anyway, the point here isn't racing, the point is what's going to be comfortable for a beginner, and it seems to me, as a matter of opinion, that a beginner will be more comfortable if she doesn't have to pedal harder just to keep up.
But thats assuming she wants to keep up. She did say she just wants to get from point A to point B and do errands, at first anyway. Going into detailed tehcnical mumbo jumbo, however good they are gives the impression that bicycling is primarilly "sport", not an alternative form of transportation. Of course, you want to be efficient, but not to the point of losing sleep over it.