With this launch, the 600,000 active developers within the Firestore community can now use existing MongoDB application code, drivers, and tools, as well as the open-source ecosystem of MongoDB integrations with Firestore's distinguished serverless service. Firestore provides benefits such as multi-region replication with strong consistency, virtually unlimited scalability, industry-leading high availability with an up to 99.999% SLA, single-digit milliseconds read performance, integrated Google Cloud governance, and a cost-effective pay-as-you-go pricing model.
Shouldn't have to replace it for a long time (if ever) and seems to work fine. More expensive than lead acid but more convenient than service appointment for a 12v battery.