The way he advances on the boat for his front flips. I don't think it would translate well to a kicker. I know it could/will be done, but it will look a lot different.
A true testament to Shapiro's greatness is that after more than a decade since a trick has been landed (and still only by him), it is mind-blowing. Could a trick that everyone (including myself) was sick of seeing him stomp week in and week out at the PWT win a double-up comp today. I really think it could.