They can be physically smaller, but they usually have much more CCA (cold cranking amps) than anything that comes in your car originally. They do not have the traditional liquid battery acid in them, so they can be mounted upside down if that interests you.
As for life span, I had one in a classic car that sat for six months at a time during the winters. The OPTIMA never failed to start the car. That battery was still showing peak CCA after almost seven years. They will recharge quicker than a lead acid type battery.
Check out the warranty of an OPTIMA. It is longer than any other lead acid battery.
If you chose to mount an OPTIMA in your trunk, they do not need to be vented like a lead acid battery.
When OPTIMA was being developed, the manufacturer provided them to state law enforcement in AZ (for the heat) and CO (for the cold). They were overwhelmingly approved by the two agencies that tested them. They were put into production after those tests.