Well there is an important caveat to that, it's been proven to exist, no one is arguing that.
But the way it affects one user to the next is completely subjective and cannot be quantified and trying to tell someone what the experience is like or will be like for them is pointless for the aforementioned reason.
I only notice it in a couple games out of the many I own and I mean exactly two when I say a couple. For you it's obviously a different experience. So there is nothing consistent about how it will affect different people at all. The best advice would be try multi-gpu and see if you find anything about it to be off.