I had a X1C bought early 2018. Not sure about the generation from the top of my head, but it had no hpdi screen. Battery life was great and Linux worked fine.

I had a X1C bought early 2018. Not sure about the generation from the top of my head, but it had no hpdi screen. Battery life was great and Linux worked fine. In early 2020 it got stolen (full disk encryption with a strong passphrase luckily). I got a X1C 7th and expected it would be as good as the previous one. The first bad surpirse was the HiDPI screen. Xubuntu did not work well with it, it required a lot of fiddling. Well and then I run some non-Xubuntu app here and there and it required extra fiddling. In the end I gave up and just reduced the screen resolution to some "classical" value and everything was fine again. Have not noticed that my code is worse because of slightly less smooth fonts... (Some distros might be easier in that aspect, Wayland is reportedly better, and to my suprise even i3 seems to work rather well.) Even worse the battery life is significantly worse than on the previous model. To my understanding higher resolution displays require more energy, there is nothing you can do. Have not checked whether the newer CPU could also have an impact. A full working day on battery is hardly possible anymore, even with little playing of videos or similar. Finally my current X1C 7th came with a 4G modem that has no Linux driver at all. Not a big deal for me because I have only 1 SIM anyway and my phone has good data rates to share. More on the anecdotal side: A firmware update was broken recently. I guess bugs happen everwhere. What I liked that Lenovo guys where active on github and a fix came quickly. Couldn't resist thinking: Like in the IBM days when Thinkpads got good support.