I've got them. Sound great and no issues with my first MOT last year. According to Mark at Abbey, the Cobras are supposed to have a better internal construction than the Berks, which makes MOT emissions fails less likely. Cold start video (with Stillen CBE):
http://vid1294.photobucket.com/albums/b617/sipar69/IMG_0051_zps6f192cb4.mp4
As with all HFCs, you may well get a CEL once they're fitted. The best way to deal with that is to get a remap and have the relevant sensor disabled at the same time. I was getting a CEL quite regularly until I had a remap and haven't had one since.