Using kickClientsOnSlowNetwork[] = { 1, 1, 1, 1 }; as per Arma 3 STABLE server 1.62 "performance binary" feedback - post #1519 causes the following to be output to the server RPT log file:

Warning Message: 'kickClientsOnSlowNetwork/' is not a value

Using kickClientsOnSlowNetwork=1; (old syntax) does not cause any messages to be output to the server RPT log file.

Either way maxPing kicks do not work.

Update to this: Works for me.

RPT Log:

19:07:52 Kicking player name='FTS Ryizo' ID=356135145, steamID=76561198223489592. Ping too high (596/ 300 ms)

Server.cfg:

maxPing=50;                     // {threshold in miliseconds}
maxDesync=1;               // {threshold number}
                                // Note: maxDesync maximal detected value is 100k (100000) and thus also max value for definition.
maxPacketloss=1;               // {percents (0 to 100)}
disconnectTimeout = 20;         // Server wait time before disconnecting client, default 90 seconds, range 5 to 90 seconds. (since Arma 3 1.56+)
kickClientsOnSlowNetwork[]={1,1,1,1};     //<MaxPing>, <MaxPacketLoss>, <MaxDesync>, <DisconnectTimeout> log and kick clients outside defined limits. 0 = log, 1 = log & kick.

disconnectTimeout seems to still use the default (90). Although, unlike before, there was no Warning Message: 'kickClientsOnSlowNetwork/' is not a value in the server RPT log file.

Launcher version: 1.5.138010

Game version: 1.64.138137 (26-08-2016)

Branch: rc

This appears to be working for me as of version 1.64.138310 (09-09-2016) RC as I was kicked for "Desync too high".

Although the arma3server RPT and console output will indicate the reason for the client being kicked, the client themselves will only see a generic kick message and thus they will not know why they were kicked from the server.

Would it be possible for the user-end kick message to include the same details that would be output to the log files?

What the client sees:

You were kicked from the server.

What the RPT and console logs may say:

XX:XX:XX Kicking player name='XXX' ID=XXXXXXXXXX, steamID=XXXXXXXXXXXXXXXXX. [Desync/Ping] too high (x/ x)

the feature isn't finished in main branch stable binaries
it's still work in progress (actual state seen in performance binaries in profiling branch)
it's not part of 1.64.RC either, only profiling / development branch ...