Here is an article by a photographer who tested both lenses. This was one of the reasons why I chose the cheaper lens. The price/performance ratio as a travel zoom is simply super.
I was on safari with the 70-300mm. For me as a hobby photographer, it fulfilled the purpose, no, even exceeded it. The weight-photo quality-price convinced me.
Only if you want to photograph at dusk, you'll have to dig a little deeper into your pocket.