Initially I put CentOS on it, which was really broken, so I swapped in Fedora which worked great. The T580 is RHEL-certified (other models are Ubuntu-certified, so it's interesting you chose Debian for yours.) Eventually I reverted to Windows 10 and upgraded to Pro.
It's now my only home computer and daily driver, for work and personal both, for the time being.
Mine has the i7 and the touch screen, I ended up I talking the seller down to $800 BIN on eBay and at the time it still had a year left on the warranty.
All in all, RAM and extra HDD I'm only in it for $1200 which I think was great deal for the last Lenovo Thinkpad that doesn't have soldiered RAM.
The install itself is pretty easy, and it is so much better than the shitty 768 panels that most of these secondhand 480s came with.
Edit: typo