Advantages:
If you made it global : Donate once for all the servers.
If you made it local : More people
might donate more, which makes a lot more money
And more servers for us players.
If it was global, you'd save : $20-100
Comments : Not bad, save a lot o' money, to buy other games
Disadvantages:
If you made it local : Donate thrice for all the servers, once for one, twice for two.
Comments : Making it local, you use more money for yourselves.
Global has no disadvantages (couldn't think of one xD) and local does.
My opinion : If you guys want more servers to make more fun for us players, keep it as local, but if you want people to be sponsors in all, make it global.
I'm voting global, but I don't really care as my mom doesn't let me
EDIT : Doesn't let me donate.