I switched to using TUIs for everything except web browsing ~8 years ago (and I switched from GMail to Mutt ~3 years ago). I honestly can't imagine going back (I'm a Linux user so this might bias my viewpoint). GUIs either feel dated or sluggish, and I find that there are far more mature and continually-maintained TUI projects for most developer-related tasks than GUI ones. This is probably because (Linux) developers have a bias towards TUIs and so write tools that suit their workflow.
Another massive benefit is that I can seamlessly use all of the same tools over an SSH/Mosh connection. X11 forwarding over SSH has never practically worked for me (it's too laggy and Australian internet makes doing it between networks basically impossible).
the remote access is the key for me. my email is on a server accessible from any machine. sure, webmail could do that too, but webmail can't keep my state if i switch devices.
i now carry a tiny laptop (gpd pocket) where i have all my important stuff, including ssh keys to servers. i use any other available device as a workstation with a browser, and use ssh/mosh to access my tiny laptop to do the important work and access servers through that.
i am not a trained typist, so i primarily type with index fingers and thumbs. that makes small keyboards much less of a problem than otherwise (before the GPD Pocket i was using an OLPC XO), and i type on it almost as fast as on a bigger one.
i got the first model of that series during their crowdfunding campaign. (it's their second product that they released 2 years ago) the keyboard on that was a bit wobbly, occasionally a key would not work (most annoying when typing a password), but for the most part it is usable.
the newer model is supposed to have a better keyboard, as i think the keyboard was what most people complained about.
it has plenty of diskspace and ram, to be practically usable, and if you got the right charger then you can hook up an external monitor and keyboard when at home or in the office, and have it portable otherwise. (and it really fits into my pant pockets)
That is worrying that keys would stop working. I'd definitely be interested in a cheaper model with an ARM processor primarily for remote development on the go.
I have the GPD Pocket 2, and I have no issues whatsoever with the keyboard except that I got some dirt spots from the keyboard on the screen easily (via each key's 4 edge points). Like, worse than my MBP 2015's.
The infrared mouse works OK (I'd prefer the thinkpoint-esque knob of the original GPD Pocket), but you can also attach a Apple Magic Trackpad 2 on it. These work very well if you run a new Linux kernel and patch up some software such as Xinput.
I run Kali Linux on it (its part of my pentest equipment; don't use it for e-mail and such [1]). Slapped an Apple logo on it for the fun of it.
Can I recommend the device? Well yes and no.
Its an OK build quality, and if you apply thermal pads and some copper you can easily run the machine without the fan on all the cores. It does get a bit more hot on the bottom then.
Its a bit expensive now, I'd say, compared to say the current Raspberry Pi 4 plus a powerbank plus a monitor. Its just 2018 price and hardware. Perhaps look at the successor(s) such as the black version or perhaps the Max?
Worst part is they screwed me over cause there's a clear spot on the top right due to attachment of the (touch)screen and in certain light / colors it is rather apparent. CS said they couldn't notice the issue. No warranty was provided. And even then I read about some people had to pay import tax once more receiving their (repaired/new) device but they want you to send the device without value (which means you could lose the whole thing if it gets lost). Typically Chinese.
[1] You could argue you shouldn't use such Chinese hardware for pentest purposes which is a fair point.
I have been looking at trying out things like Vimperator to get a feel for no-mouse web browsing. But that looks even neater, I'll definitely give it a shot. :D
I do use Vimium (Firefox port) as well. I actually don't use Browsh much myself because I don't have a reliable, publicly accessible server available where I could run it.
Another massive benefit is that I can seamlessly use all of the same tools over an SSH/Mosh connection. X11 forwarding over SSH has never practically worked for me (it's too laggy and Australian internet makes doing it between networks basically impossible).