I have heavily tested both scanner here at Panthera.
As precision both Medit t500 and DOF UHD are amazing scanning in term of precision.
The software of both can do everything, love the DOF for their expert version.
Speed, the Medit is quicker then DOF if you are into massive production.
I had to discuss with both team directly and honestly nothing wrong about both.
We at Panthera decided to go with Medit for 2 factor : Size of scanner, Medit is half the height of the DOF and speed as said Medit is quicker then DOF.
We use multiple T500 about 10 hours per day non-stop and they are very reliable. Cannot talk about this with DOF since I didn't push this side of the questions.
Thing said, in precision and quality don't be afraid both are amazing. (Same precision as 3shape D2000, even a little little more according to our test)
Honestly the first question is to check how good is your re-seller. Both scanner are at risk to break, don't take the story in this post as granted, they are both of good fabrication and have the same risk to break, what will make the difference is how good the re-seller will support you if this happen.
Enjoy your shopping!
Best