Using Ubuntu 14.04LTS for one year on a T450s (20GB, 1GB SSD) - it has two batteries and you can switch one of them while running the system on the built-in bat

Using Ubuntu 14.04LTS for one year on a T450s (20GB, 1GB SSD) - it has two batteries and you can switch one of them while running the system on the built-in battery. With the big battery I can work the whole day without having to charge, something like 10 hours are possible for coding and working on documents and running some VMs. I consider it the best laptop I ever had.