I'd almost flip-flop your conclusions. I'm a little dubious about a "city slicker" being able to put on the same 15k miles / year as somebody who puts on more highway miles. If you don't put enough miles on it, that battery pack is going to get mighty stale. If you have to factor replacement batteries in there, the calculations can be pretty skewed.

When we were looking into new options to supplement our MSSQL servers, we settled on Mongo. We were aware that Postgres will act as a document store in addition to being a traditional RDBMS, but our decision was largely based on 2 things: We acknowledge that we'll likely never be able to completely eliminate our use of MSSQL. So, if we need an RDBMS, it will still be there. The other main factor was that Mongo makes replication, failover, and sharding a snap, relative to other systems. We don't have a DBA to implement replication for us. So, the simplicity was a huge factor. There are billion ways to store your data, and they all come with positives and negatives. Postgres can pretty much be everything to everyone, but like any system where that's the case, it can be harder to configure (for me, a developer, anyhow... I'm sure DBAs are laughing at me).

because I have a genuine interest in solving problems. That interest doesn't stop at 5pm. I don't feel the least bit "used" that I use my own time to tinker, and learn no things that ultimately benefit my employer. I feel much more satisfied learning things than I would if I spent that same time watching a lot of TV. That's also the same reason I listen to audio books while working out. Learning things IS my hobby.