Spies don't help get CV's back, because if a carrier has been MIA for more than about 4 hours, theres a good chance that you'll need a dedicated mission to get it back, and the level of caring isn't high enough to put one together from scratch. Generally you'll need a fairly large squad to form the backbone of the mission, with whoever else joins just adding their weight to whats already there.
They also report the location of CV's that were orgionally your country's when you don't hold the port, so they can sink it and go hide the CV in a different corner, and not let it out even if they end up capturing all the bases your country has.
-100
However, spies do help bust those stupid NOE missions, so that earns them about a +100. If we could instantly disconect everyone who joins one of those stupid things, I'd say go for it.
On the other hand, they also bust legitimate missions that intend to use tactics and skill to take a base, which generally start good fights, where the advantage goes back and forth, and actually moves. The busting of those missions also tends to start a big counter-horde, that generally ends up plastering the hangers at nearby bases, and swarming the town with M3's.
Everything all totaled up, you've got about a -200 for spying, which means if we can discourage it, we should.
3hrs would let people change countrys for fights, and it would also discourage spying by country-swapping, as after 3hrs, you can't really bust a mission that started 15 minutes after you changed countries.
