Installation of the 6.0(1)E1 major version results in a complete re-imaging of the sensor. While the sensor configuration settings are maintained, all data written to the event store as well as any unsupported customizations will be lost.
If you have been actively monitoring and configuring your 4.1 version then the upgrade path would be preferred.
This way your current configuration can be converted automatically during the upgrade to work with the higher versions.
If your sensor has a lot of tunings it could take several days trying to do this conversion manually from the older 4.x commands to the newer 6.x commands; so you would want to let the upgrade scripts do the conversions automatically for you.
But, if your current 4.1 version has just been sitting on the shelf or has very little site specific configuration, then a fresh installation of IPS 6.0 from a System Image may be the way to go.
This way you won't have to worry about any upgrade issues or what somebody else put on the box months or years ago.
For instructions for installing a System Image refer to:
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...
[toc:faq]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 and UDP are I...