The thought is always start with the simplest capability you can use to meet your requirements -- PG is awesome, but it does require care and feeding by a DBA. Here's a tool to migrate from SQLite to PostgreSQL if and when necessary, but if your schema is reasonably clean it shouldn't be a hardship:
https://github.com/dimitri/pgloader
My suggestion is script what you need to test to check throughput for the number of concurrent conns you think you'll be needing and base decisions on that. FYI - I use Fossil SCM over git. It is awesome.