It's possible that whoever mapped your ecutek has not done a good enough job.
Stick with the ecutek, it's currently a much better product.
The cobb is not faster than the ecutek, they both access the same ecu. Conditions may have been different, there might be an unrelated problem with your car, the fuelling batch might be worse or most likely the new ecutek map is not as aggressive as the cobb's was. Or it could be psychosomatic.
Absolutely, Iain wouldn't let you go away unhappy. That's not how he operates.
The danger is if your Cobb felt faster because the map was more aggressive but potentially too aggressive, in which case Iain may have mapped it safely, but as a consequence it was further from the edge.
Have a word with him, he'll explain this to you. The key thing is that if the mapper is competent, there's nothing to choose between the products. The performance will just be the level of compromise he and you are prepared to settle on. It's a balance between performance and engine longevity.
One thing I'm confident about is that Iain is the most competent ecutek gt-r mapper in the country, and probably in the world. He's certainly the most experienced.