I had used the Mac privately and professionally for a living since around 1987, as a typesetter, graphic artist and software developer. My harddisk contained all private and business data and had never seen a fresh install since the first version of MacOS X - I was successfully updating the OS ever since. Shortkeys were of course in my muscle DNA and I new every file in the Library-folders by name. Hard to imagine to leave that experience for good. But I got so concerned about Apple's way into entertainment electronics, that I was commited to leave in time.
Hardware-wise I switched from the MacBook Pro 17" first to a Lenovo Thinkpad W520, and four years later to my current Tuxedo XUX707. Both computers I liked a lot, but the Tuxedo I really love. It is a beast with 32GB RAM, 4TB HD, 256 GB SSD, desktop i7 7700, 4K monitor and a dedicated Nvidia 1060. It is heavy and loud, more a gamer PC than a laptop, but performance and reliability are incredible. I have two external monitors connected to it.
I prepared the transition for about a year. First I tried a couple of Linux distros (on a second partition of my gaming PC) and after a while I decided for Ubuntu. I made sure to execute at least one major distro update of my final selection of Linux candidates to make sure they ran flawlessly. My favorite was Linux Mint, but it failed on one of the upgrades and so I ended up with Ubuntu. Unity was never an issue for me.
Then I investigated how to transfer my mails (some ten thousands), but I had used Thunderbird already on the Mac and so there was no trouble at all. Next I transferred my data to the Ubuntu test machine and played a while to find, how well I could continue with my daily chores. Turned out to work quite well. At that time I was not much into graphic design any more, but much into software development. I found comparable software for everything except Adobe InDesign (Scribus just won't do). I replaced Lightroom with Darktable, Photoshop with Gimp (do not like Gimp a lot, but it works for my needs) and later Krita, Illustrator with Inkscape and Microsoft office with LibreOffice (and later Softmaker).
Not all of the replacements had the same quality as on the Mac, but they were ok, at least no showstoppers for my commitment to switch. In many domains, especially development, text processing and the like, I was overwhelmed how many good (and many free) solutions were available in the Linux world. It was sort of enlightenment. Of course, there was a lot of new stuff to get used to: application installation via package managers, shortkeys and the like.
After about 3 months of "playing" with the prepared test system I decided to switch and I knew that I would have to switch hard. I was very afraid to end up living in two systems. So I decided for a D-Day, did a last synch of data and put the Mac in the shelf. Yes, the first month was hard, but as I was commited to never return, I just went through and it worked. Today, I could not imagine to ever return to the Mac.
I never had crackling sound, blinking screens or anything like this. My Linux computer can connect and handle much more hardware than any Mac I ever had. It is very possible (and likely), that certain computers will not work well with Linux - this is something you have to make sure with a test installation before you switch, but it is for sure not a generic issue. I switched to Tuxedo because they offer Linux-tested hardware (and they build the computer as you want it). The worst hardware issue I ever ran into was lacking support for keyboard lights.
There are occassional issues with the proprietary nvidia-drivers, though, that can really drive someone mad. I know how to handle this by now, but this was the only real annoyance I ever encountered.
One word of warning, though: I have always been a developer since my childhood and I was pretty experienced on the commandline long before I switched to Linux. This might give me an attitude and advance that other Mac users might be missing and that might make a transition more difficult. While the standard Ubuntu system will be sufficient for most users out of the box, there might arise the need to fix or enhance or adjust things and while this felt very natural for me with my background, it might be a big hurdle for others.
My setup today is: I live completely on the Linux laptop. I still have a Mac on the desk for compiling iOS apps and casual use of Adobe InDesign. I use the "Das Keyboard" keyboard with unlabelled switches and the synergy keyboard sharing software, so I can use the Linux computer and the Mac as one computer. I have the keyboard-layouts and shortkeys of both operating systems in my muscle DNA now and in addition a good deal of the Emacs-shortcuts ;-)