I am not a DHCP expert. I just needed to setup a failover system for dhcp and to my luck, dhcp-3.0 supports failover/load balancing it self. My configuration is fairly easy (especially since I only have one big subnet).
This distribution includes support for failover protocols, DDNS updates, conditional behaviour, classing, separate address pools with different access permission, and various other features. (That last sentence was taken from isc.org's website (credit is due where credit is owed, after all, isn't that what open source is for?))