I have reviewed both of these cameras for uwpmag.com and those reviews can be found in the back issues section. Since these reviews both cameras have had significant firmware upgrades which have added additional features to each camera.
I still think that E-M1 is the better of the two cameras, it is more robust and has better speed in all areas although not by much. Apples to apples the Nauticam NA-EM1 housing has more features built-in to the base housing cost, such as included hand grips, front and rear vertical triggers for front or rear auto focus control and more.
Both Housings will use the same ports, gears and extensions for the listed lenses so the cost differences are in body (both in about the same price range at this time) and a $400.00 difference in the cost of the housing until you start adding to the E-M5 II housing.
Regarding waiting, I would rather be shooting now. A new E-M1 (II) is likely to be announced at Photokina in September 2016 for release in the first quarter of 2017.