Guilin in mid-April - EM1 and lenses?
The obvious one you've missed is the Olympus 12-40. Maybe you were thinking of that when you mentioned the 12-50, but they are two different Olympus weathersealed zooms.
The Oly 12-40 and Panasonic 12-35 are similar in specs and price. The Oly 12-50 is quite a bit cheaper but slower. It is also weathersealed though.