Personally if you can get a brand new kit which looks and performs the same as its much more expensive (and i would suggest massively overpriced by the manufacturer who are making a fast buck from it) then i would save the money and buy the copy.
I see what you're saying, and yes, its true to a degree, but dressing your car up in desirable dress and performance parts is almost totally about bragging rights. Having the best of something.
For most of us on this forum anyway, we don't all TA our cars and rely heavily on performance.
I'd rather have a genuine AEM than a fake, un-proven Gruppe 'M. What if the case splits after 5'000 miles, you will be stuck with the bill of getting something else. I've not heard of a single problem with a GM, in regards to reliability, the carbon is perfect and the fixings are also.
By all means get one and prove me wrong, but at the end of the day I would still save my money and have the real thing.
It looks the nuts and sounds amazing, its expensive for a reason.....its the best.
Its like clothes, you'd perhaps feel better in a Hugo Boss suit than a Tesco look alike, they both do the same thing. But one will do it better.