This means you need a caching system. You need to keep track of which records have been sent to which server.
Why?
1st case - the splited server is hub - after the split timestamp is exchanged and all the records after that timestamp propagate thru hubs, then to other ("regular") servers
2nd case - the splited server is "regular" - after the split it's hub sends all the info, and all this can be done in a way which prevents using services on splited servers, just like there's options to forbid new chans while splitted
If I've got you right,all this tracking is useless,well not exactly useless - of course in that way it will prevent any possible differences, but the price is too high as you've said. On the other hand, I don't beleive (and I don't know for sure) something like this is used with basic events like privmsg, and even without that tracking they work just fine
And one last thing - I don't beleive this is an issue for largest networks. One of the main reasons for this idea was to prevent abuse - not that I'm saying there's no abuse on top10, but on small networks way to many ppl try to play god, abusing every single feature they have power over. So by your calculations, less 10mb for 5000/2000 network will prevent abuse - this is too small price!
