I can't speak for OSX VM in Linux, but when I ran it last year on an XPS 15 in Windows 10, it was better than tolerable. I had 2 cores and 8GB of RAM dedicated to the VM. I did have to turn off animations in the Apple UI, to get it to run like normal. The only issue I had was that I was unable to get Messages to work in the VM. I didn't try very hard, though. Although I prefer OSX to Windows 10, I kind of stopped using the VM because it was one more hoop to jump through that didn't make that much of a difference in terms of my kind of usage. 50 percent of the time I'm in Windows, anyway, to play games in Bootcamp. The only thing holding me back at this point is the anticipation of loud fans and middling battery life for the XPS. If I got it again, it'd be 32 GB of RAM and the 4K screen, both of which suck power. The new model does have a larger battery, though...and most of the time I'd be plugging this thing in and have it on a laptop cooler....
If you want to keep the fan noise down it might be an idea to go with the FHD version, the 4K ones get considerably hotter (both the screen drawing more power but mostly the GPU working harder to update 4x the area compared to a FHD). I did set my sights on a 4k screen too as I really like the retina screen, but then I found some 13-14" FHD laptops while browsing in a store, and the screens actually look super good. I think the lost battery life, scaling issues, extra heat and so on isn't really worth the tiny improvement in text clarity and such. Better to get an external HiDPI screen for when you use it docked imo.
But yeah, OS X in a VM for any must-have applications (at least during a transition period) seems like a good way to go.