Interesting interview with DHH, where he talks about how they made the new Basecamp feel very fast without using a lot of Javascript (most of Basecamp still lives on the server). The two tricks they used are PJAX and Russian Doll Caching.
Rails Long Term Support
Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)
Prevents you from data breaches and liability risks