RE: what is the benefit??
A soft cam has a much smoother draw cycle. Pull back a soft cam @70lbs and you'll find it to be smoother than a hard cam @60lbs!
Other than all the benefits that Arthur mentioned , I myself choose the soft cam to prolong my shooting as long as I can! I'm sure thats the same case for alot of the shooters on here. If I had a dollar for all the shoulder surgeries that I've seen other shooters at the range and on leagues have to go thru over the years I'd be rich!