...and you're an excellent cook on top of it. So, I will continue using the garlic press.
I wouldn't. Even pre-chopped is really different than the press, which mashes every bit of the garlic on the way out.
Alton Brown had a great explanation of this on an episode that was all about Garlic: the chemical responsible for that great garlic flavor loses a lot when exposed to the air, and oxidizes somewhat to boot, which can cause bitterness. The smaller you cut up the garlic, the more you lose.
Each way of eating garlic - whole, roasted, sliced, diced, pressed, liquefied, aged - presents a different and complex flavor. I can definitely tell the difference between sliced and pressed garlic. Try it next time you are cooking some and I have no doubt you will be able to as well.
Does it make a big difference? Probably not. But I always try and make my home-cooked fare as tasty as the stuff we get when we go out... keeps the wife happy