https://www.mecum.com/lot-detail/CA0816-244561/0/2007-Ferrari-599-GTB-Fiorano/6-Speed/ Another 599 manual, this will tell if Amelia Island was a fluke of two guys "seeing whose is bigger", or confirm the rise of manuals across the Ferrari spectrum.
There was a manual 599 that went for auction at Villa d'Este a couple months after Amelia which IIRC went for a bit less. I think the one at Amelia was a fluke. No doubt will they command a premium due to the rareness of them, but not a 5x factor.
At the Pasadena Concorso last month, CNC had two manuals, both 2007's, selling for $599k. I asked a young sales guy if there was any real basis for the mark-up. He said "there were only 20 manuals made in the 599, so we can ask whatever we want".