Canon 17-55mm f2.8 VS Nikon 17-55 2.8 on BMPCC6K Review ?

I have bought the Canon 17-55 2.8 IS lens after using the Nikon / Nikkor version for a while including a two week trip across Jordan and some extreme weather conditions over there. Actually I ordered the Canon lens during the trip as I discovered a few shortcomings of the Nikon one. Biggest one being the lack of image stabilisation and no electronic aperture control (a useful feature using on BMPCC6K as it saves the settings in metadata). Not only that - but the BMPCC6K&EF mount adapted to the Nikkor 17-55mm f/2.8 is not technically correct as the flange distance increases from what the lens was designed for and therefore introducing some technical flaws like increased amount of chromatic aberrations and not being able to focus to infinity (although the latter was not so much of an issue in real world). So what are they like compared? I would say Nikon is a tad sharper but not when it comes to extreme / near infinity focus (due to earlier mentioned issue relating the EF and Nikon F adaptation). Also Nikon has a slightly warmer to red/magenta colour cast and is a little bit brighter, meaning that either the Canon version is more like f/3.2 or Nikon is closer to f/2.5. I have also witnessed that in the depth of field being ever so slightly narrower on the Nikon lens. Also Nikon has a more "onion ringing" going on in its bokeh balls especially visible when shooting in dark and at closest focusing distance with bright lights in the background. And lastly Canon is producing...