Until recently, my daily driver was the T500 (the larger screen version of the T400 in the article), and it worked fine for everything except GPU.
(I actually downgraded to the T500 years ago, because I was pissed off about the Intel Management Engine.)
Recently, I upgraded from the T500 to the T520, which is the last ThinkPad with a non-chiclet keyboard. It works fine for everything except GPU and fitting inside many backpacks.
With ThinkPads of this era, you want to get a high-spec variant of the model (e.g., top-res IPS display), and then make the following upgrades:
* SSD
* run Linux
* run uBlock Origin (and block most of the third-party surveillance, which hurts performance) (JS runs fine, so long as you're not running multiple dueling adtech slimeballs' intimate mouse trackers)
* max out the RAM (you don't need that much for Linux, unless you're using an exceptionally bloated desktop option, but it's cheap, and you can use it to keep filesystems like ~/.cache off your SSD )
* (optional) replace the CPU with a more optimal one for power draw or heat, or maybe for compute (these are socketed in most models)
* (optional, not for the faint of heart) install Coreboot, and then you have more WiFi upgrade options