Anything else that stands out as a benefit? I have a side hustle, so it seems like it might be nice to have a bit of separation of worlds
Are you looking for a technical argument? In the past, desktops have offered significantly more processing power, better GPUs, internal expansion, internal storage etc. That's far less true of the modern Mac range - if we ignore the top end Mx Ultra Studio and Mac Pro, everything else is offering the same range of processors, with the same RAM and storage options, and no internal expansion. Desktops may have a slight performance advantage over laptops because of better cooling (although Apple sound determined to make the Mini smaller) but that's not "night and day".
The main remaining desktop advantage seems to be slightly better connectivity c.f. corresponding laptops - which comes down to whether ethernet ports and USB-A are useful to you, and gets a bit swings+roundabouts if you factor in needing to connect at least one display to a desktop. I'd say only the Studio (with 4xTB, 2xUSB-A, 2xUSB-C/3.2, 10G Ethernet and SD card) has an unmitigated advantage there. Still, you can get close with an appropriate hub/dock for your laptop, and although adds an extra I/O bottleneck, its questionable whether most people would notice.
I think the question of whether you should have a second machine are all about your personal preferences:
- Having a separate computer to keep personal use and "side hustle" insulated from the day jpb may be a good idea (depends on what your work culture is like).
- You've said you want to leave your 'work' laptop at work occasionally - on those occasions, does that mean you want to leave your work at work?
- Does syncing two computers via. cloud (or working in the cloud) every day work for you? Depends on what you are doing (I used to have a bunch of local web servers set up for web development and syncing took a bit more effort c.f. keeping a few Office docs in the cloud - keeping video projects in sync might also be inconvenient - but some of my habits were formed when fast internet wasn't so ubiquitous).
The question then, is whether your home machine should be a desktop or a laptop. Does your "side hustle" or personal use ever involve travel? I'd only consider a Mac desktop if I were fairly sure I had no use for a personal laptop.
Over the years I've vacillated between having a
work-supplied desktop + work-supplied laptop + home desktop (back when laptops were less powerful),
work-supplied laptop + home desktop,
work-supplied laptop + personal laptop (...after knackering myself re-locating a classic Mac Pro four times a year)
own laptop for work and home (...easier than getting my old work laptop upgraded!)
own laptop for work + personal desktop (...not sure how that happened!)
personal desktop + phone (...here'es to semi-retirement!)
...and they're all perfectlt cromulent solutions.