efnet, being efnet, allows some dumb things, like unscanned proxy ridden networks to leaf onto the network, sure. But the majority of competent servers knock these drones down before they even begin to be a problem. This is why you befriend an ircop. Don't you know your police? Vigilante justice only? I'm sure you dial 9-11 or similar whenever 50 guys run into your house or at least it's on your mind. Why isn't the same thing on your mind when 50 drones flood your channel? Now I'm not saying run into #chanfix everyday and cry 'please help me get my channel back' cuz you opped one of them. But if you have some of these people with similar interests as your channel name indicates, residing in your channel (an ircop or two who you give fringe benefits to), this problem eventually takes care of itself. That's all i'm saying... I personally find running scripts of this sort as a drain on resources and the wrong person playing god. God should be played by the network/ircops, not by mere users/bots...
Migrating involves collaboration. Channel heads should talk to each other to discuss the impact these drone/spam bots have on their channel. Eventually migration will be mentioned and a date can be set, and bots can be set up to keep topics with new server infos/channels, and then the migration on the date you pick happens automatically without user intervention. This would be easily scriptable....in fact, wait, it already was back when we migrated 2 dozen channels from newnet all at the same instant..Even had a relay.tcl within the bots still on the old network so any stragglers who chose to stay behind could still chat with us and us with them (albeit without the dcc features of chat/get/send and the other networks nicklist to see).