if all you are doing is bashing around the yard,or even a bmx track go and have a look at the Traxxas Stampede.they are one of the most fun and most durable trucks on the market.
http://www.rctech.net/forum/showthread.php?t=179764
this thread has a heap of movies featuring stampedes so you can get an idea on how tough they are.my pick would be the VXL Stampede (brushless)

mini lst might be a bit small for backyard work being a mini and all.

emaxx is a good truck as is the e savage but both require 2 batteries to run etc.