I'm currently able to solo 60, but it's more efficient to grind around 55. Outside of Leoric'c Crown + ruby, what are some gear changes I could make to increase my experience gain without losing too much killing speed?

http://us.battle.net/d3/en/profile/Zeus-1247/hero/62257501

Should run with a full group if you want to farm exp...
Preferably with a xp heal monk and/or xp support barb

Or try using those if you want more exp.. but id go with option A
Hellfire Ring
Leoric Rong
3 Piece Cain set
3 Piece Born set

this