I'm kinda torn as to how I feel as far as an opinion goes on this. It's not a bad suggestion and certainly "doable". where my issues lie is as such:
1> your example uses the client quit message that is displayed to all the channels your "victim" was in at the time of the akill. You example displays the nicks also affected but may not have anything to do with and of the channels your "victim" was in. To me that is an invasion of privacy that everyone deserves. Other non-opered users do not need to know who was akilled with your "victim". The akill is in the quit message of the victim as an explanation as to why the person left suddenly.
2> #2 is where my love for resource conservation comes in. The question I always ask first is: Is this "feature" worth having? In my humble opinion .. no. Which I'll explain in #3.
3> Most and I mean most, not all
Most ircds, today have some form of searchable /who list where you can, as an oper, search for users by IP or host and gain the very list of nicks you are about to akill. Since there is a good chance your IRCd already does this, why not take advantage of it?
4> Since services uses session limiting and most modern ircd's only allow a set number of users connect from the same IP, you list "victims" shouldn't be all that long in the first place.
5> One ircd that I know of has this neat toy called a TLINE command. The TLINE command is kinda like a "test run" or a sandbox if you will where you plug your host into the command and run it. The ircd does a little magic .. errr .. research .. and tells you how much "damage" you command will cause.
I would say that something like the TLINE command added as a module would be beneficial and at the same time satisfy your request without violating the common courtesy that everyone deserves.
