There are IRCD's out there with built in flood protection and throttling.
I know UltimateIRCD and Unreal3.2 Both have nick change throttling to stop those dastardly bots nick flooding. You can also stop people from nick changing in your channel with a channel mode flag. Plus you can define how the server deals with channel floods on a per channel basis. You can even get the channels to strip colours deny ctcp commands as well. There are addon modules too, spread across the net which could replace sentinel but that takes effort and some people just prefur to use eggdrops, as I do