I dunno. I'm not sure how you decide a K is "elite." Seventh in Career FG% puts him behind Kaeding, Vanderjagt, Bironas, Graham, Gould and Hartley. Are they all elite? He's way down the list in FG's made (82nd), but that only says he's only played six seasons and plays for a team that tends to put the ball in the End Zone. He's been nearly flawless in PAT% (fifth all time) but he's way down the list of PAT's made (74th) too because of his young age.
So, I guess I'd say about Gostkowski that I'm damn glad he's the Pat's K, that I'm never nervous when he comes on to tack on the PAT, but that the jury is out on what he would do if everything was on the line in February (which is not to say he wouldn't nail it).
I do know that Number Four is going to Canton, however much or little we hear about him.
Not only has he put up solid numbers (eighth in career FG's made and 13th in career FG% over a 16 year career), but he made what is regarded as the greatest Kick under pressure in the history of the NFL (that breathtaking 45 yarder into a gale of a frozen ball that just dove over the cross bar and dropped like a rock three feet later sending the Snow Bowl into OT) and then went on to make the game winner in that game as well as in two SB's with time running out or down.
He might have had chances that others didn't or haven't, but when he had them he got the job done. How else do you measure greatness"
And, to answer your question, Number Four was the first person to kick a walk-off SB winner and, while there were a couple of seconds on the clock when he kicked his second one, he effectively repeated the feat. With those kicks and four rings, he is in a class by himself as a Kicker.