The T420 has been my main daily driver for nearly 6 years (using it right now to type this!) and I super excited to check this post out in more depth as battery duration is one of my biggest personal complaints about the system.
To those wondering about the T420, they are fantastically rugged and I still think they are the best laptop on the market assuming you can handle either a slightly crap monitor or the hassle to upgrade it. I've dropped them onto concrete, dremeled them, even lit them on fire, most of the time they'll take the abuse but even when they don't, they are dirt cheap so who cares! Ebay has them listed at $150 a replacement, you can literally buy nearly 10 of them before scratching the entry point for a Macbook. All of this while being able to a modern web-dev development setup thanks to it's incredibly simple upgrade bays.
What do you put in the upgrade bay that helps with web development? I upgraded from an x220 to x230 (modded to take the x220's classic keyboard) because the lack of hardware h.264 decoding in the '20-series CPUs was causing noticeable performance problems with web content.
I have a i7 4 core, 16gb, 512 ssd, 1080p, gpu accelerated, coreboot system.
I'm waiting on the open hardware platforms to come around to something like it before I upgrade. And I don't really feel the need to, apart from not having a 4 or 8k screen.
Pretty easy, but a bit expensive considering the laptop itself only costs around $150. A 1080p display + adaptor board for it costs about $100 and the 1440p display + adaptor is around $150. If you look up "T420 ips mod" you'll find lots of pictures and tutorials.
To those wondering about the T420, they are fantastically rugged and I still think they are the best laptop on the market assuming you can handle either a slightly crap monitor or the hassle to upgrade it. I've dropped them onto concrete, dremeled them, even lit them on fire, most of the time they'll take the abuse but even when they don't, they are dirt cheap so who cares! Ebay has them listed at $150 a replacement, you can literally buy nearly 10 of them before scratching the entry point for a Macbook. All of this while being able to a modern web-dev development setup thanks to it's incredibly simple upgrade bays.