Using a lesser known client can reduce banrates -- I strongly believe that Jagex categorizes people into clients and flags then bans them all knowing they're all using the same bot client. Dreambot tries their best to avoid these cluster bans by making each account uniquely interact as a bot but it also doesn't help with thousands of users using it anyways. Covert mode is not only a better interacting system, but a lesser used one too and helps reduce banrates even further.
Just to confirm, people have botted 80 hrs + straight with Covert. I don't know if it's as good as it was though.