Is the EM5’s Miss-Stated ISO concerning to you?

On my E-PL5, for fixed aperture/shutter speed/ISO settings, it underexposed compared to my other cameras.  This review also found the OM-D underexposes about 1/3 to 2/3 a stop for the same settings: http://photographylife.com/reviews/olympus-om-d-e-m5 (camera comparisons tab)  When you push exposure by that amount to compensate, that means you have that much less headroom to work with along with introducing additional noise.  In real world use this is a non-factor because the deeper DOF of the smaller sensor affords larger aperture settings as well  as the IBIS compensating for slower shutter speeds.

But I get tired of reading people claiming that the OM-D/E-PL5 is neck-and-neck with Sony Exmor APS-C sensors in ISO performance.  There's nothing to indicate that the OM-D uses different (read: better) sensor technology and a smaller sensor isn't going to magically overcome the laws of physics by gathering more light than a larger sensor.

This is just like the DOF debate.  Point out differences in the sensor and the flames come out from everywhere.