Uh if you go down the many mice one reciever route... why on earth would that make sending replies to whispers any harder?

What I did with three: (Briefly as I was borrowing machine three and the mice.)

Main keyboard and mouse muliplexed with Multibox (the synergy variant). To loot drag wireless mouse to top left corner of screen (any corner will do) that lines up all the cursors. Then loot as normal with that mouse. In my case shift plus right click, one of the three characters loots the other two don't. Take control of main screen again with normal wired mouse and kill another mob...

BUt as mentioned its not the looting that sucks its the amount you need to grind to get 20 drops, assuming a 1 in 10 drop rate (average) for 20 drops thats 1000 mobs to kill (i think I suck at maths though). And while grinding sadly is part of the game I'd rather be doing kill quests.