Help choosing Olympus OM-D E-M5

I believe you may want to look at some reviews of the original 17mm f/2.8:
http://slrgear.com/reviews/showproduct.php/product/1276/cat/14
http://www.photozone.de/olympus--four-thirds-lens-tests/468-oly_17_28

http://www.dxomark.com/index.php/Lenses/Camera-Lens-Database/Olympus/Olympus-MZUIKO-DIGITAL-17mm-F28/
http://www.lensrentals.com/blog/2012/05/wide-angle-micro-43-imatest-results
(the last is a roundup of m43 Imatest results:

The current 17mm 2.8 has pretty soft edges and corners even at its best f-stop which don't do the OM-D sensor justice:

DxOmark's resolution field for the Oly 17mm 2.8 at f/4:

I'd recommend looking at the Panasonic 14 or 20 pancakes, or 25 normal for purchase over the current 17mm, unless you have to have that focal length now .