Having a responsive website means you don't have to worry about prospective clients leaving your site due to lack of information or accessibility. The trouble with having a separate mobile site is that it's essentially a 'readers digest' version of your desktop site, and since we spend an increasing amount of time on our mobile devices, this minimalistic approach is no longer ideal. 

We want to provide website visitors with all the information they need, and give them no reason to click away from your site.