Below you can see a quick RAW to JPEG conversion (but otherwise untouched) of the sample shots from my test with the Canon 135mm F2 L lens.
(Unfortunately the Canon 70-200mm did not stop full open when changing lens like the 135mm lens did) Both shots where from a tripod, and the distance from the tripod to the subject did not move in between shots.
The Metabones speedbooster show quite a bit of vingetting, as previously observed in this article here. But otherwise a nice image quality. With the Metabones Speedbooster which is a focal length reducer the lens in first reduced by 0.71 and then multiplied at the Nex crop sensor by 1.5 making the 135mm into a 143mm f1.4 (but shot at f2 for comparison with the other adaptor)
Unfortunately the Fotodiox adaptor is passive, and so the Exif data is not carried over. But as it is passive it also ensures that the lens was shot wide open at f2.
And with only the passive Fotodiox adaptor and the Nex crop sensor the lens becomes a 135mm x 1.5 = 202mm f2 Canon L lens. And with barely any vingetting.