Is anyone using the LB Clustered servers with a Web control panel?

I know that several control panels are offered, but will cPanel work, for example, without some serious modifications?

cPanel does not have a cluster configuration right now. I think the only control panel that can is h-sphere BUT I am unsure if it is for that type of load balaning. Generally people who use a hardware load balancer are hosting a single website instead of a lot which it sounds like you may be doing. The multiple websites can get a lot more complex.

yep, 0 problems just remember to create the same account in both servers.

I believe it is more like cPanel has some clustering features, but it is not yet fully implimented.

We've found that your best option is to create an A record in the DNS entry for your cpanel / whm client site, i.e.:

cpanel.yourclientdomain.com
whm.yourclientdomain.com

And have the cpanel or whm entry pointing to the IP address of your primary physical server (not the IP of the load balanced cluster).

You'll either then need to edit the scripts so they create the account on your other server, or just create the account yourself.

You'll also need to setup replication using unison or rsync. We found rsync to be quicker and more reliable than unison.

Regarding the cpanel clustering features, from what we can see, these are for DNS replication only, not for account / server replication.

we use another method for accounts, not related to which control panel you use in our case.