Anyone Install Lithium ion Batteries? Results?

I have 2 Optima AGMs that will be in service for 6 1/2 years this spring. They are still strong as of last season.Plus they have stayed in the RV outside in winters. Possible longevity reason could be the 125 watt solar panel which keeps them topped off and minimises discharge. AFAIK AGMs are not subject to the fire issues of lithium and are probably cheaper. And definitly better than the old leads. Why not just go AGM?