I have been working with several customers running in MP mode, and this is - if available for your environment - definitely a recommendation. For details please see the System Configuration Guide, starting on Page 155. It gives you some idea.
Please let me know if you have further questions.
The only thing worth noting is that some of the dashboards and a few of the reports behave badly in MP mode. Otherwise our experience in moving from standard mode to MP mode has been good.
Please note that activating MP mode makes troubleshooting a lot more painful. In MP mode, MWG "clones" your configration, your logs, basically everyhing, as many times as you have processes. In our example, we have six processes, you we get 7 new folders in /opt/webwasher-csm:
Each of those icap-x folders contains it's own log folder, and the pain with this is that they are actually being used. So each process in a MP setup logs to it's own directory. If you need to troubleshoot something (say via the access.log), you will have to deal with 6 access logs instead of just one.
Those logs are consolidated into /opt/webwasher-csm/logs every couple of minutes or so, but that's where the next major pain in the back is starting: these things are not documented anywhere. You have to guess what's going on.
My experience with McAfee support staff on this matter is also very bad. Running MP makes things much more complicated. We had a McAfee trainer in house for some training the other week, and when he found out we were running MP he couldn't explain to us how to properly troubleshoot such a setup.
So beware. You gain a lot of performance, but you pay with a badly supported, complicated and badly documented setup.
We have few devices that works in MP mode.
Also we have opened a few service requests and i dont see confused support staff.
tail -f /opt/webwasher-csm/icap-?/logs/access.log | grep something
The choice is yours...
If your hardware is compatible I would certainly recommend Multi Process mode.