When I started shooting sights, I'd already shot 'instinctive' for many years. I don't know whether it was the right way or wrong way, but I always looked through the pin (which remained pretty clear, even though I didn't focus on it) and kept my concentration on the target.

Now, I can't see the pins any more whether I try to concentrate on them or not, without reading glasses anyway, so I took the things off. I don't have the precision accuracy I had with them, but I still do good enough to beat most sights shooters on the 3D course.

I guess it mostly depends on whether you use the pin as a hard sighting point or merely as an elevation reference. As long as your form and anchor are correct, you should shoot down the middle whether you've got sights or not.