I am moving this thread to Firewalling but as far as I know the answer to your question is that with the 5505 you could actually configure ports as trunks because they were L2 ports so the native vlan setting was relevant.
However with the 5506 the ports are L3 only so you can't configure as a trunk so the native vlan does not really come into assuming you are not using the native vlan for data.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...