You can disable "Display marks of excellence" option, this makes ALL MoE invisible to you and enemies.i guess that solves the problem of ability to focus on marks.
As of 1.7 CT #2, the Anonymizer feature doesn't hide marks of excellence for players who enabled it, so enemis will se your MoE even when you use the anonymizer.
Source: I checked it in battle @ test server.
This means it's still possible to target dangerous enemies (e.g. via mods showing gun marks on enemies), which somewhat makes the new feature moot. I think it would be better to hide gun marks when enabling Anonymizer.
See the edit, it's possible to turn off marks which is effective for both you and enemies.