That would be a fun project idear: a personal electrum label synchronisation server... Run a little deamon on your vps to synchronise your labels on all your machines...

I guess it wouldn't be to hard to do either (eventough i wouldn't call it a simple project): Pick trough electrum's sourcecode and see how the external synchronisation protocol works, then build a little daemon that does the same as the "real" synchronisation server.
The downside would be that the user would have to run a modified version of electrum, since his/her own synchronisation server would have to be hard-coded into electrum's binary instead of the current synchronisation server. Or maybe editing the hosts-file on the user's machine would be sufficient if we don't run into issues with invalid certificates (add a record that points the current synchronisation server to your vps's ip).

Something to try out on a rainy day