i drove my FG Marder in snow.. works great.. i did seal the radiobox with silicone and the servos got some silicone on them also=)
so now it's waterproof:P i think all the clones also have a radiobox for the reciver... so they are 80% waterproof ofcourse water can still get into the servos if you try getting it to swim
i would go with the Duratrax Firehammer since it's an product you easy can get parts for