I backed out of a K5 system when the E-M5 came out, smaller, lighter, same IQ, similarly weather-proofed. Found it nailed focus better, less noise at high ISO, and better all-round quality control of gear. (Not so good on the ergonomics, though, and no control over the ramp up of auto ISO which I used continuously on the K5 to get the balance I wanted for particular situations.) Sadly, no equivalent of the excellent Pentax support Web sites in Oly land. Closest are
http://www.slrgear.com/reviews/showcat.php/cat/2
http://www.lenstip.com/Main_page
I run the kit Oly 12-50 when its wet outdoors, gotta have it. Otherwise the 14-150 lives on the E-M5 95% of the time, plenty good enough for (diagonal) 50" canvas or 20" photo paper prints, instant focus, great flexibility in range.