I too switched from a 15" MacBook Pro, same general time-frame as the one you mentioned. I got the Librem 15" and 13" and, to be honest, I like the 13" better. They are pretty similar in specs but the keyboard layout of the 13" is more like my old MacBook Pro. The main reason I looked to switch is that the new Apple laptops are just no longer made for me. I hate the new keyboards, especially the touchbar gimmick and therefore lack of Esc key, etc. Anyway…
The biggest con I’ve noticed is the screen. You get pretty spoiled by the MacBook Pro “Retina” screen. But, I can deal with it.
Next up is the touchpad. It actually didn’t take too long to get used to it, but the Librem touchpad has a much rougher texture. Two-finger scrolling works fine, you might have to toggle a setting to flip the scroll direction depending on your preference. I found the “coasting”, or the amount of travel when flicking the scrolling, isn’t as great as with the Mac. I’m guessing this is more software than hardware and might get fixed, but it is what it is now. Also, the two-finger “back” and “forward” gestures simply don’t work anywhere I’ve tried. Again, I’m guessing this is software but I haven’t dug into it enough to either make it work or find out if it just hasn’t been implemented yet. I haven’t had any problems with the palm detection and typing.
I’m a back-end developer, I don’t do much GUI / WebUI work, but I do type a lot. I find the keyboard to be perfectly fine, if only a tiny bit less that the old MacBook Pro keyboard. It’s waaaaaay better than the newest MacBook keyboards. I have a bit of difficulty with the left shift key ignoring me from time to time (if I hit the extreme wrong edge of the key), so it can still use a little bit of improvement. It also has no capslock light indicator. But, I have typed on the keyboard exclusively for days’ of work, and I’m happy with it.
I do tend to use my external keyboard / mouse / huge monitor more often than not. Here the HDMI-only video option is a bit limiting. I can’t run at full 4k mode because that’d mean only 30hz refresh rate, which is just awful to work under. 
So I run at 2560x1440, which ends up fine for text sizes too and I don’t have to try to get Linux apps happy with HiDPI – HiDPI is still an issue with LInux, but it’s getting better every month or so.
I have no idea on the weather resiliency, sorry. Mine is mostly used indoors.
Of note, I do not run PureOS, I run free-mode Debian, which is just installing Debian and answering “No” to the “do you want to use non-free repositories?” question. The only reason I do this is that I’m a long time Linux user and I prefer to run stripped down systems and slowly add the stuff I need, avoiding as much “cruft” as I can. PureOS has one install option, and that has lots of “stuff”. 
I understand that this is mostly just my eccentricity, but it works for me. I use a stripped down install of KDE and I use the Firefox browser, just downloaded from Mozilla and manually installed. I use a lot of firejails for privacy reasons (most people would not do this). I also use a lot of virtual machines using libvirt/kvm/qemu and that works wonderfully (I used VirtualBox on the Mac, and Fusion for a short time).
I also use Krita with my Wacom tablet and love it. This set up for digital art is every bit as good as what I had on the Mac, which surprised the heck out of me. This is even more true if you can get Krita 4, which was just recently released.
I also do a lot of music creation / sound design BUT I haven’t been happy with any LInux-based options here yet. Playback is fine, I just don’t like the freedom-based creation tools available. This is probably just a personal preference thing though; I’m quite used to Ableton Live at this point.
Oh that reminds me, one last warning, the headphone jacks on my Librems appear to have a design flaw. They are very noisy when I also have the power adapter plugged in. I thought it might’ve just been faulty shielding on the first Librem I got, but it’s the same way on my second one, so I’m guessing it’s just a design flaw. This is important if you ten to use headphones while coding while plugged into power. Luckily, I don’t do that as much these days, but I used to and it would drive me crazy.
BTW, updates on most every Linux distro are pretty easy. Most have a GUI tool that will notify you and you click to update, just like on MacOS. You can also do, for example, a quick ‘sudo apt get update ; sudo apt get upgrade’ once a week yourself if you don’t prefer the GUI options.
Final thought: Yes, I’m happy with my Librem and it works great for me, which just a few caveats. I’m sad about Apple’s direction, but I’ve moved on now.