the advantages are,
you can leave it totally discharged for years on end (and have it last longer while doing so),
looking at the specifications, it should outlast a battery by a large amount if not under continuous use,
and they weigh way less and take up less space than batteries that put out the same current
I can buy a battery now to use now,
but I can't buy a nice AGM starting battery for use in 15 years from now
I know that you can get some flooded cell batteries dry, so it solves that issue some
my real motivation is that I just got tired of having the battery die in my car about every 2 to 3 years (I got my standby current down to 10 mA, so at least it is not that part of the car making them not last), now the batteries would still run lights and things like that, but would not start the car when it gets cold. could be that I drive my car about once a week and not daily.
the quality has dropped so low on most batteries made by exide, and they make most of the batteries I can get local.
the capacitors will vastly outlast the more pricey regular car battery that the local places sell.
I get that this all is less of an issue for the radio hardware unless I am doing a solar setup that is also portable