Lets assume:
1. client_cmd(0, "hideradar") You don't like because it switches off the radar for the client without his permission and he is not able to see the radar anymore. Well because I'm very bad guy and I don't believe in everything what I can read (even if it's written by so big authority person as You ;) ) I've tested it and what I saw is this:
a) if You use "disconnect", then just after that You connect to another server - that's true - the radar isn't displayed.
b) if You use "exit" function then You connect to another server the radar is displayed normally.
AMX version uses hideradar since long time before KRoT@L started maintain the new topic for it and there was no complain about that in the old topic nor in the new one. In the new topic there was already more than 20000 downloads, then someoone hacked their forum, so KRoT@L had to re-upload the file again, so now You can see only about 800 downloads. So - I believe this is not so serious problem we should completly reject such option like hideradar.
2. Tampering with radar messages and changing their info about teamplayers positions may really affect game playing (I mean speed of the server) if it's done in *.sma, but if You could make it in csdm module it should work much faster and shouldn't affect the speed of the server...
3. Forget for now about my complaints (because I'm always complaining
) - just why that user - topic-starter - was complaining then if he shouldn't see the issue with the scramble work of the radar? If he was complaining, other people may complain about that, too.
This what is the problem/issue for some person doesn't need to be the problem/issue for another person.
My final proposal is - like You mentioned it before - for now I can add the option scramble/hide radar for ffa with default scramble (I don't think the option (0) with leaving the radar for FFA enabled as it is for normal game deserves to be there - but maybe You know some reasons why it should be also there?) and the people will be able to use it or not if they will want. If it will be possible and You will have time in the future - You can think if it's possbile to hack radar messages in csdm module to clean the radar (make it empty for the user).
But as always - the final word and the decision is up to You.