acera is entry level for a bike maker like trek, but above the quality of a walmart bike. for that usage, i'm sure that a dual sport would be just fine. the main value for your money is in the frame quality and design and in the wheelset.
if you want an alternate suggestion, i'd buy an older name brand used mountain bike and factor in the cost of a full tune up at a bike shop. i would try to find a lightly used, older, higher end cross country hardtail with rim brakes and front forks (1995-2002) for about $200. if you hunt around, you will get a bike that is as light as the dual sport that can also handle trail riding. bikepedia is an excellent place to look up the specs for used bikes you find on craigslist.