I would always choose a Mac Pro over a Macbook if I have a choice, -always.
Don't get me wrong, Macbooks are great machines. But they wear down a lot faster because of the battery, they tend to heat up very fast,(thermal throttling) and they are just a bad choice on the long run when it comes to real tough render work. They are nice in the first two years, ok in the third but real bad from the fourth year of use on.
(In the past) A Mac Pro can be used for a decade.
Since Apple removed the internal SSD port on the 2017 macbooks and all other ports on the outside (except USB-C) you are screwed once your mainboard breaks in terms of data.
On top of that you can't update a thing. Then this crappy T2 Apple chip comes along, good lord! Another Apple trap to screw you. You need a docking station from the start. Back in 2010 it was a different game, so I got a 17' back in the day.
Great machine and all, but today those things are so much worse on the upgrade side. The only reason I cold use my Macbook for 8 years was the upgrade path to more ram and SSD as well. Not possible anymore. If I have a choice, I always choose the desktop version. If you are not much of a road warrior or a snake oil salesman, go stationary.
In your case, I would keep the 5.1 for sure and just go for a 13' MBP as an additional device.