AmigaOS 2.x is what you use until you can put a 3.1 ROM in your Amiga. The only reason for using it is if you don't have 3.0 or 3.1. I don't see any advantage to it at all since 3.x is just as fast and efficient but much improved and updated.
I think any OCS/ECS Amiga is more useful having a Kickstart ROM switcher and both 1.3 and 3.1. 2.x is kind of useless.
