An Air Herald publication states that “jailbreakers according to the team hacking Evad3rs they should stay away from iOS 7.1.” The reasons are not known, and the webσελίδα mentions that maybe the group is disbanding.
According to the publication in question, the team does not provide a reason why jailbreakers should not upgrade to iOS 7.1, but it likely has to do with the fact that Apple has closed all known vulnerabilities of iOS. Since iOS 7.1.1 replaced iOS 7.1, the same warning applies to newer firmware.
The post adds, "... one of the team members reported that evad3rs seems to be no longer focusing on iOS 7.1 as a team," suggesting that it is probably in disrepair. It certainly won't be the first time a dev-team doesn't agree with all its members on a project.
The notorious Dev-Team, which is a member of the famous pod2g hacker, was broken up and then reunited, adding some new members to the place they abandoned to become evad3rs. Always according to his publication Air Herald it seems that this group has done its circle.