Distil Networks is more like a CDN (Content Delivery Network), so every traffic to customers website should pass through Distil server. In other words you have to point your DNS to their CDN (that can potentially bring down your site). They keep analyzing your website through out and if the traffic is found malicious they block.

As you asked about competitors, ShieldSquare as a potential alternative, offers following benefits over Distil:
Non-intrusive API integration that will not affect your website performance and uptime.
Zero False Positives that will ensure that your genuine users are never troubled.
I can offer more direction if I know more about your environment.
Best Regards,
Steven