Mine never lasted more than 4 years without losing capacity. I never particularly enjoying changing out those big heavy monsters, adding water to them, keeping them charged, equalizing, draining them below 50% or worrying my battery tray would collapse.
I'll be brutally honest here. I have more money than I'll ever need. I like new technology, things that make my life easier, and not having to maintain acid batteries is one of them. I also recently bought a 3200w Outback inverter, the best on the market. I like good stuff that lasts a long time.
My hobby doesn't require me to worry about money. I like it that way.