Earlier quoted context omitted.
Agree. I’m not sure the exact years, but starting around 2013 the T series screens were awful.
Starting with the *40 gen they changed from LVDS to eDP screens and got access to better screens. This was the start of 1080p being available at 14" where it was only in 15" models before. There's a panel from one of the Razer Blade laptops that was popular to put in the ThinkPad T440p. 1080p IPS. Looks nice. On the older models you can also do a mod to sacrifice your DP port for use internally with an eDP panel. The…
The X220/X230 mod uses the docking port's DisplayPort lanes, instead of the DisplayPort port. I'm still able to use the DisplayPort port on the X220.
The T420/T430 converter doesn't use DisplayPort, but simply converts LVDS to eDP.
I used the B140HAN01.3 (AUO panel) for my T420, which my friend also got for a T440p. Colors and viewing angles are great on it, likely the Razer Blade panel you mentioned.
The X220 mod was a pain to install IMO - soldering to tiny solder points on the motherboard, soldering the sense wire which needed burning off the enamel from the enameled wire, and having to cut out (I used flush cutters) parts of the top case for the new display to fit. My first install wasn't great either, with a cold joint causing issues I solved later on by reflowing the joints.
The AUO 14" panel has better color gamut (IIRC 100% sRGB coverage) than the available 12.5" panels for the mod.