In diablo 2, I could have two sets of weapons equiped and could easily toggle between them with the W key (a dps set and a mf set).
Is it possible to equip multiple sets of weapon in diablo 3, with a key to toggle quickly between them?
No, there is no such option in Diablo III.
(Blizzard decided against it after they found out that during play-testing, players tended to switch to Magic Find gear just before landing the final hit on a boss :)
You can set up macros to hot swap gear sets prior to boss kills, chest loots etc.