There are plenty of good reasons to go to an AGM. The double to triple the service life is only one of them. My first AGM gave me nine years.
In storage the AGM loses very little. My AGM sits, disconnected and untended, November to April and retains enough power to operate landing legs upon reconnection.
Zero maintenance other than annual terminals cleaning.
Yes they cost more. Much more. Given what they are over the 100 plus year old technology of the wet cell the AGM is worth it.
There's a reason why they are used in aviation and marine applications.