I moved from a MBP where I lived in the Apple garden since OSX came out. I have been all Linux all the time now, for the past year. I have tried the great Linux Desktop experiment almost every year since 1999. Finally 2018 was the year of success! I do still have an iPhone but Librem is not available yet. That may go too.
I must qualify this by saying I run Manjaro on my Librem 13/v3. I tried pureos but need a less strict OS to live in and work in daily.
I bought my Librem13 for the openness of hardware and the overall company ethics. If you are coming from a Mac you already pay a premium for hardware. Purism is less of a premium and to be honest I am not sure it is a premium as it holds up like a champ. There are cheaper machines but a clean Bios and hardware that just works is worth the extra, for me.
The biggest loss for me is Messages. The integration of the phone and laptop messaging is very nice. But not a deal breaker, obviously. I have retained some icloud services like calendar and contacts.
I work as a software developer and don’t use any proprietary software that cannot run on Linux which may be a deal breaker for some. To be honest look at alternatives before you just decide you can’t change. There is a lot of great software out there for Linux.